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DIGITAL PRESSURE CONTROLLER

1. i request 1000 serial write commmand read the response ay E E request 2000 serial char 7s Ine X3 Cher em CLOCK TE Starty Current write 7000 serial s Write Command 1 0 while 1 lt QUEUE SIZE es n start clock while inq in inq out Wait for a character Current clock if current lt start 0064007 if current statt gt TIMEOUT Check for timeout butftfer r return FALSE ch angueue Put character in buffer Lt Ang oub QUEUE S EZE ing couEb 05 if ch Line Feed End of response buffer i 0 return TRUE else buffer i ch butter OURUBR SIZE X 0 B ffer full return FALSE 5 6 4 SAMPLE PROGRAM 4 QBASIC EXAMPLE FOR 7252 REM SINCLUDE C GPIB PC QBDECL BAS DIM READING AS STRING 30 CALL IBDEV 0O4 0 12 1 8H402 R70102 CALL 7010 CALL IBWRT R7010 MEAS chr amp HOA CALL IBRD R7010 READINGS PRINT READINGS CALL IBONL R7010 0 END Note EOM amp EOS are linefeed 5 21 REMOTE OPERATION THIS PAGE INTENTIONALLY LEFT BLANK REMOTE OPERATION 5 22 SECTION 6 0 MAINTENANCE 6 1 INTRODUCTION Very little maintenance is required tor the DPC This section of the manual discusses suggested mainte
2. 4 11 ea AE tee 4 12 2 6 1 2 Menu Setup Use oboe umen 4 12 NEN sas 4 12 4 6 1 2 2 Bar Graph 24 2 4 13 4 6 1 2 3 Ready e dde 4 13 4 6 1 2 4 Gas Head Pressure 4 13 AO AIOS PNET e ue 4 13 4 4 13 4 6 1 2 7 Changing the Number of Decimals 4 14 KEV ee ode 4 14 AG Ned Ment 4 14 4 6 1 4 Menu Setup Remote 4 15 AOTAN 4 16 4 16 4 6 1 4 3 Serial Interface 5 4 16 Menu Setup tA dade 4 16 Dalel TT 4 16 250 1 9 em redet unas 4 17 MENG irc dice p 4 17 2 5 2 1 Calibration PassWord ssi I 4 17 4 18 MENU PROGRAM STORING A SEQUENCE IN MEMORY 4 18 Preparing eR RI ue Dd 4 19 4 6 3 2 Entering a New 4 20 4 6 3 3 Automatically Generating a Program 4 2 4 6 3 4 Changing the Name of a
3. 4 22 4 6 3 5 Changing an Existing Program 4 23 4 6 3 6 Changing the Configuration Stored with a Program 4 24 PROOF 4 25 MENU I TE SE 4 25 4 6 4 1 Menu Test Sweep 4 26 26 4 2 Menu Lest Self Tests 4 27 4 6 4 3 Menu Test Remote 4 27 A044 Meno Test sois sei 4 27 4645 Menu 4 28 MENG 1 DISPLAY TEE 4 28 4 6 5 1 Menu Display 4 29 4 6 5 2 Menu Display 4 29 4 6 5 3 Menu Display Blank ceat usta e our Rio tero 4 29 X INTRODUCTION SECTION 5 0 REMOTE OPERATION 5 1 5 2 5 3 5 4 5 5 5 6 6 1 6 2 6 3 6 4 CAPABILITIES 5 1 5 1 NEUE 5 1 REMOTE LOCAL 5 2 CONFIGURATION 2 5 2 DEVICE MESSAGES tabe 5 3 54 1 SCPVCOMMAND FORMAT 5 3 5 4 2 SCPI RESPONSE FORMAT
4. aaa ii COPYRIGHT NOTICE 00070204 iii REVISION NOTICE vt totius oet Ren vido pera vf het Ribes iv REVISION 5 00 00 vi SAFETY SUMMARY Vii TABLE OF CONTENTS iere epa P y ERR pa M uuo tu dv Vili SECTION 1 0 GENERAL INFORMATION 1 1 1 1 1 2 GENERAL INFORMATION 1 1 1 3 FEATURES 1 1 1 4 STANDARD EQUIPMENT amp OPTIONS 1 3 SECTION 2 0 THEORY OF OPERATION 21 e 2 1 22 POWER SUPPLY eee bee LE dun te 2 2 2 3 ELECTRONICS 2 2 BACKPLANE BOARD a 2 2 2 3 2 MICROPROCESSOR 2 2 2 3 3 DIGITAL CONTROL BOARD 0 2 3 2 354 IEEE499 INTERF
5. 4 5 4 1 2 SELECTING MODE OF 4 6 4 1 2 1 Simulated Absolute 4 6 MAIN MENU eee peta ed Raid fied te tesa 4 6 CONTROLLING PRESSURE 6 bri cesar edes 4 7 4 371 SETTING THE PRESSURE SETPOINT 4 7 4 3 2 ENTERING EXITING CONTROL 4 7 4 3 3 ABSOLUTE ZERO OF DEVICE UNDER TEST OPTION 4 7 ____________ _ _ _ 6_ 4 8 STEP JOG 4 8 SOLER PING E 4 8 AO SIC 4 8 AM ecc Gates orient 4 8 eec 4 8 Mp mtt deines 4 9 Meno ooa eost Remis 4 9 gt essen obs pedis 4 10 EVAN acetone 4 10 PN VENT PERRO TEE 4 10 1X INTRODUCTION 4 6 2 4 6 3 4 6 4 4 6 5 COME Bodo cessere ute treo 4 11 4 11 Supply COMECHO Ml 4 11 oo 4 11 Ie WIS
6. 6 3 29191 ties 6 3 6 4 1 2 6 6 6 4 2 VACUUM NEGATIVE GAUGE CALIBRATIONS 6 7 6 4 3 RPT CALIBRATION SIMULATED ABSOLUTE 6 8 6 4 4 VACUUM SENSOR CALIBRATION OPTIONAL CASE REFERENCE iieri ote Dru oo Used see e Breda eek 6 9 6 4 5 EDITING THE CALIBRATION COEFFICIENTS 6 10 UC 6 11 6 4 6 1 Gauge and Vacuum Negative Gauge Instruments 6 11 6 4 6 2 Absolute Mode with Evacuated Reference 6 12 1 INTRODUCTION 6 4 6 3 RPT Simulated Absolute Instruments 6 13 GAGA A E 6 13 6 5 SENSOR PHOTOCELL 7 6 13 6 6 OPTIMIZING 6 16 6 7 FAN 6 18 6 8 SYSTEM SOFTWARE UPDATE PROCEDURE 6 19 6 9 REPLACEMENT 5 6 20 6 10 PRESSURE INTENSIFIER 6 21 SECTION 7 0 PREPARATION FOR STORAGE amp SHIPMENT 7 1 DISCONNECTING THE 7 1 7
7. q Module A Primary Dual Range Transducer Module SENSOR Photo SENSOR Isolation Section Sensor BOARD Valve DC 2 6 1 Section Barometric I 2 6 2 Reference EE 27252 CES M eeec SPEO TTA POWER BACKPLANE pote BOARD DIGITAL ection ection CONTROL 2 2 22 Section 2 3 1 BOARD Section 2 3 3 MICROPROCESSOR BOARD FRONT RS 232 Section CARD 2 3 5 Section 2 3 4 IEEE 488 ______________ ___ Electronic __________________ ee Primary Dual Range Transducer Module REF SENSOR Photo SENSOR PNEUMATICS Section Sensor BOARD 2 6 1 Section A Section 2 4 262 TEST a a TEST Module B SENSOR Primary Dual Range Transducer Module D ene ey a pean ge a Ac QUT ESTEE ae SENSOR Photo SENSU Section Sensor Valve 62 ym BOARD O Section 2 6 2 ______ _________ pem Miu PORT POWER BACKPLANE POWER SUPPLY BOARD DIGITAL AC POWER Section Section CONTROL 2 2 2 2 Section 2 3 1 BOARD B Section 2 3 3 I Electronic Module B FICUKE 4 1 DPC BLOCK DIAGRAM 2 THEORY OF OPERATION The 8 range 72505 5 has two pneumatic control and tour dual r
8. return 0 Goroxy Gly 5272 cpruntt Zeroing while status amp 1 0 gotoxy 9 Aer return 12 EE See x CHECK errors display all GPIB and 7252 error messages return TRUE if any errors were found M M Check errore unsigned char status int retval e x Check for GEIB Interface Errors UE x if ibsta ERR cprintf GPIB Status 4X Error d r n ibsta iberr return 1 E E Check for 1252 Errors j C x retval 0 while kbhit t ibrsp device amp status7 if status 7 6 4 0 break retval 1 request 7000 Ty cprrnur REMOTE OPERATION 5 16 Serial poll Check error bit Get error message return retval Ll uu E LI write 7000 wiube ur to the 7250 E E NEE ae ee Se ee E VOLE wr gste 7000 char S ibwrt device s strlen s RR request 7000 write a query command and read the response uA a a rel ecrire iii Acc Bequest 7000 Onar WS ibwrt device s s
9. 5 3 5 4 3 ANSI IEEE 488 2 1987 COMMAND SUMMARY 5 4 5 4 4 SCPI COMMAND SUMMARY 5 4 544 9 EXAMPLE SCPECOMMAINDS 5 9 9 450 SGPLSUATUSAREGISTEROS i veteri CU mta sa 5 9 SERIAL OPERATION ERR did cuba oben 5 11 SAMPLE PROGRAMS 5 11 5 6 1 SAMPLE PROGRAM 1 7252 GPIB IEEE 488 CONTROLS PRESSURE OOO TGS 5 11 5 6 2 SAMPLE PROGRAM 2 7252 GPIB IEEE 488 ZERO vacio 5 14 5 6 3 SAMPLE PROGRAM 3 7252 SERIAL RS 232 CONTROLS 20 00075 5 17 5 6 4 SAMPLE PROGRAM 4 QBASIC EXAMPLE FOR 7252 5 21 SECTION 6 0 MAINTENANCE INTRODUCTION cscs 6 1 OBSERVING THE SOFTWARE VERSION 6 1 PREVENTIVE MAINTENANCE 6 1 6 3 1 INITIATING THE DPC S SELF 6 1 6 9 2 REMOVING THE DPC SX OVER 6 2 ______ 6 2 6 944 PARTICLE FILTERS 6 2 VACUUM PUMPS item ie eeu 6 2 673 0 PROCESSOR BATTERY 6 3 CALIBRATION 6 3 6 4 1 CALIBRATION INSTRUCTIONS
10. 1 lt lt intnum OULDOEED ws outportb portbase 1 0x01 Enable receive interrupt outportb portbase 4 0 Enable Interrupt DIR BIS serial write CLEAR serial close turn off serial receive interrupt ie up PNE CEDE SE oN VOL Serial Close unsigned v Outportb pert base 2 299 outportb portbase 4 0 V AnNperth 0x21 v k lt lt OUtDOELb 0X21 2 Old wectob s p RR serial write write a single character to serial port E EE E NE E eee eo eee E void serial write char ch while ltransmit enabled while inportb portbase 5 0 20 0 OHtDOIUtbD GI write 7000 serial write a string to the correct 7252 J nc Serie if address 1 serial write CLEAR Disable Addressing REMOTE OPERATION 5 20 else serial write DLE Enable Addressing serial write address 0x20 Address while s 7x Weite string serrdl write
11. 2 5 2 NORMAL MODE In the Normal mode minimizing pressure overshooting takes precedence over control speed In the Fast Mode control speed takes precedence over overshooting the set point In the Normal mode the inner loop controls to the set point using maximum rate until close to set point and then slowing down as the set point is approached to minimize overshoot The outer loop continually adjusts the inner loop to compensate for temperature and drift 2 5 3 FAST MODE This mode of operation assumes that the inner loop sensor and the outer loop are aligned When a new set point is issued the outer loop sends a signal that was determined to be equivalent to the desired pressure When the system detects that the pressure is sufficiently close to the desired set point then the outer loop switches to the PID algorithm This control mode results in the highest soeed pressure control 2 5 4 ALIGNMENT OF INNER LOOP WITH OUTER LOOP 2 7 THEORY OF OPERATION Since the control system of the DPC is based on the alignment between the inner and outer loop sensors there is a procedure that automatically aligns these sensors It is possible that during typical operation the alignment between the inner loop and the outer loop sensor can become miss aligned This can cause control problems such as overshoot This can be realigned using the Auto Tune feature See the Maintenance Section Section 6 0 for details on the Auto Tune functions of the 725
12. 8 When you first enter the Calibrate menu the top left hand side of the display will indicate which sensor is being the viewed The sensors coefficients are then shown below the sensor label On the 7250sys there are multiple dual range primary pressure sensors The first sensor that is shown is the primary measuring sensor A This is indicated by the word A Primary displayed in the top of the display To cycle through the various sensors that exist in the system you would press the Sensor F6 function key Assure that you are in the screen that is labeled A Primary or the desired range depending on which channel is being calibrated 9 To begin the calibration process press the Calibrate F2 button the calibration access code is enabled enter it at the prompt The first calibration screen will appear NOTE To exit the calibration procedure before the calibration coefficients have been changed press CANCEL any time during the procedure Canceling restores all previous calibration values Step 1 1 1 The first step automatically performs the sensor zeroing routing MAINTENANCE 6 4 1 2 until the zero procedure finishes This may take several minutes When the DPC completes step 1 the calibration screen will appear Step 2 2 1 To begin step 2 use the calibration standard to apply the various pressures that will be requested by the 7250sys There will be 5 primary calibration points per dual range sensor The
13. Gauge 2 0000 0 004 of Each Range 0 003 of Each Range Stability Over 3 Months Over 1 Year 0 0019 RDG 3 months 0 0075 RDG year lt 0 004 of Range 24hrs Control Stability Active Control Mode 0 001 of Controller Range Passive Control Mode 0 000 of Controller Range Control Low Limits psig 0 15 psia lt 20 Seconds Precision is defined as the combined effect of linearity repeatability and hysteresis throughout the operating temperature range Some manufacturers use the word Accuracy in place of Precision however the meaning is identical 3 Requires vacuum pump to control 0 psig or the vent mode can be used to obtain 0 psig Zero drift typically improves with sensor age gt Defined as 10 FS increments into a 15 cubic inch volume APPENDIX A A 6 GAS SPECIFICATIONS Pressure Source Medium Clean Dry Air or Nitrogen Pressure Source Particle Size Contamination lt 50 microns Pressure Source Max Moisture Content 50 C dew point Pressure Source Max Hydrocarbon Content 30 ppm VACUUM REQUIREMENTS Supply Vacuum 50 liters per minute minimum with auto vent feature absolute units only Bypass Supply Vacuum Valve for High Pressure Gauge work Industrial grade nitrogen 99 5 pure A 7 APPENDIX A THIS PAGE INTENTIONALLY LEFT BLANK APPENDIX A A 8 APPENDIX B SUMMARY OF ERROR MESSAGES Negative error numbers are the Standar
14. For Simulated Absolute instruments the Reference Port is monitored by a precision barometric sensor Figure 2 2A This sensor provides the barometric offset that allows the gauge mode sensors to function in the absolute mode When operating in the simulated absolute mode the lowest range sensor that the system can select to operate in the absolute mode must have a full scale pressure range of 14 7 psig 101 kPa 2 4 1 1 2 Absolute with Evacuated Reference Optional An option is available on the 7250sys that will allow a gauge mode instrument to operate in the absolute mode by evacuating the sensors reference port with an external high capacity vacuum pump This option includes a vacuum sensor that is internally tied to the reference port of the pressure channel that is configured with this option Note each sensor in the system must have a vacuum sensor installed to operate in this mode In gauge mode the reference port is open to atmosphere In the absolute mode a vacuum pump evacuates the reference port of the sensor Once a vacuum level of less than 200 mtorr is achieved the operator can zero the 7250sys The 7250sys would zero the Ruska quartz sensor against an internal vacuum sensor measuring this residual vacuum level This vacuum sensor continuously monitors and update the pressure reading based on the reference vacuum level Following the absolute zero the channel would operate in the absolute mode If the 250sys requires
15. MODEL 7250sys MULTI RANGE SYSTEM USER S MANUAL DIGITAL PRESSURE CONTROL SYSTEM MODEL 7250sys USER S MANUAL RUSKA INSTRUMENT CORPORATION GE RUSKA 10311 WESTPARK DR HOUSTON TEXAS 77042 713 975 0547 FAX 713 975 6338 e mail ruska ruska com E http www Ruska com Release 7250sys 1D01 Revision A Date 02 06 04 WARRANTY Ruska Instrument Corporation warrants its products to conform to or exceed the specifications as set forth in its catalogs in use at the time of sale and reserves the right at its own discretion without notice and without making similar changes in articles previously manufactured to make changes in materials designs finish or specifications Ruska Instrument Corporation warrants products of its own factory against defects of material or workmanship for a period of one year from date of shipment Liability of Ruska Instrument Corporation under this warranty shall be limited to replacing tree of charge FOB Houston Texas any such parts proving defective within the period of this warranty but will not be responsible for transportation charges or consequential damages This warranty is not made for products manufactured by others which are illustrated and described in Ruska catalogs or incorporated in Ruska products in essentially the same form as supplied by the original manufacturer However Ruska Instrument Corporation agrees to use 15 best efforts to have original suppliers make
16. The 7250 5 has two full scale pressure ranges and two pressure controllers integrated into one instrument 1 3 FEATURES The following features are available on all Model 7250sys DPC s Multiple Ranges of Fused Quartz Bourdon Tube Sensor Technology GE Ruska s force balanced fused quartz Bourdon tube sensor makes use of the stability high elasticity low hysteresis and excellent fatigue strength of fused quartz The 7250sys integrates multiple ranges into the system The system automatically switches between these ranges as it controls pressures selecting the most accurate sensor to perform a pressure measurement NIST Traceability All DPC s are calibrated using GE Ruska deadweight gauges which are directly traceable to the National Institute of Standards and Technology NIST GE Ruska is also a NVLAP accredited laboratory and therefore can provide an optional NVLAP accredited calibration Universal Power Supply The DPC s universal power supply accepts AC voltages between 90 and 260 volts and DC voltages between 100 and 370 volts To reconfigure the DPC for use in another country the user simply changes the power cord Measure While Control The DPC simultaneously digitally displays the commanded pressure the actual pressure and the difference between the two The system integrates 1 1 INTRODUCTION multiple controllers and automatically switches between these controllers to enhance control performance throughout the ran
17. Consigna Diferencia 110 000 Consigna Mesure 0 000 ps Diff Consigne 0 000 Difference 110 000 Consigne 7250sys Change Language Hold key for 5 seconds Espa ol FX Francais Italiana Japanese Recall 0 000 0 000 psi psi Diff Setpoint 0000 110 000 Difference 110 000 setpoint lessen Misure 0 000 0 000 psi Differenz psi Diff Sollwert 0 000 Setpoint 0 000 Differenz 110 000 Differenza 110 000 setpoint 0 000 psi F 0000 AAS 110 000 Vi INTRODUCTION SAFETY SUMMARY The following are general safety precautions that are not related to any procedures and do not appear elsewhere in this publication These are recommended precautions that personnel must understand and apply during equipment operation and maintenance to ensure safety and health and protection of property KEEP AWAY FROM LIVE CIRCUITS Operating personnel must at all times observe safety regulations Do not replace components or make adjustments inside the equipment with the voltage supply connected Under certain conditions dangerous potentials may exist when the power control is in the off position due to charges retained by capacitors To avoid injuries always remove power from discharge and ground a circuit before touching it DO NOT SERVICE OR ADJUST ALONE Do not attempt internal service or adjustment un
18. For each channel never apply more than 120 of the DPC s channel full scale as a pressure supply Both pressure supplies must be regulated and meet all of the criteria stated in Appendix A of this manual 3 Never apply more than 11096 of the DPC s full scale to the test port of each channel Never try to control while a pressure source is connected to the test port 4 Do not expose the instrument to thermal and mechanical shock or vibration This may affect performance and require rezeroing 5 See the safety summary in the introduction 3 4 POWERING UP THE DPC First plug the power cord supplied with the DPC into the power connector on the DPC s back panel CAUTION Grounding for the DPC is provided through the power cord Next plug the power cord into a receptacle rated for any AC voltage between 90 and 260 volts If a different power cord is necessary for your receptacle consult Table 1 1 for available power cords Finally turn on the DPC by toggling the power switch on the back panel When the MEASURE screen appears on the display the front panel will be fully operational 3 4 1 OBSERVING THE DPC S FULL SCALE RATING The full scale pressure range of the DPC is noted on a label on the front panel of the instrument 3 5 PNEUMATIC CONNECTIONS The following sections discuss each port All ports are 4 inch NPT pipe fittings See Figure 3 1 Remove all plastic shipping plugs from the back panel pneumatic ports 3 5 1 PRESSUR
19. VACuum Sensor A Vacuum VACuum1 1 Sensor B Vacuum VACuum21 Sensor C Vacuum VACuum31 Sensor D Vacuum VACuum41 Sensor E Vacuum 1 Sensor F Vacuum 2 Sensor Gas Temperature TEMPerature11 Sensor B Gas Temperature REMOTE OPERATION 5 4 EMPerature21 3 1 EMPerature41 5 1 2 12 EMPerature22 3 2 4 2 5 22 CALCulate PRESsure TARE VALUE number STATe ON OFF LIMit LOWer number SLEW number UPPer number VENT number CALibration MODE MODE number Sensor C Gas Temperature Sensor D Gas Temperature Sensor E Gas Temperature Sensor F Gas Temperature Sensor A Oven Temperature Sensor B Oven Temperature Sensor C Oven Temperature Sensor D Oven Temperature Sensor E Oven Temperature Sensor F Oven Temperature get set tare value set tare state using current press low pressure limit slew rate limit high pressure limit auto vent limit calibration edit enabled request calibration edit The next section of calibration commands are valid for the following main sensors PRESsure5 PRESsure15 PRESsure25 55 5 2 PRESsure45 PRESsure55 VALue n number DATA 2 VALue n VALue n number CALibration
20. When controlling pressure below atmospheric pressure a vacuum pump is required Supply vacuum lines must have minimum restrictions Tubing should have a minimum l D of 4 inch In small rooms the exhaust port should be piped outside to prevent an accumulation of nitrogen It is also very important to install an auto vent valve to the vacuum pump The purpose of the valve is to vent the vacuum to atmosphere when the pump 15 turned off 3 5 3 TEST PORT The device s under test is connected to the test port The DPC controller is designed to operate within its specification limits into load volumes from 5 to 60 80 to 1000 Excessive leaks in the test volume will cause measurement errors in the device under test and may possibly affect control stability Tubing connected from the test port to the load volume should have an internal diameter greater than 1 8 inches 3 mm Tubing should be shorter than 15 feet 5 meters when smaller diameter tubing is used The 7250sys automatically switches all of the various pressure range sensors and control channels internal to the system to the single test port 3 5 4 REFERENCE PORT The reference port is open to atmosphere for gauge measurements or it can be connected to the Reference Port of the Device Under Test Instruments with a low full scale pressure range require special handling to assure the performance of the instrument These instruments are very sensitive to atmospheric pressure chang
21. unauthorized entry into the calibration section of the system Please refer to the Maintenance Section Section 6 0 of the manual for more detailed information regarding the calibration of the DPC The calibration menu is identical for each dual range sensors Press the Sensor function key to select the desired dual ranges sensor to be calibrated 4 6 2 1 Calibration Password The calibration password allows the user to protect access to DPC calibration constants and the calibration procedure If the calibration password is set to any number other than zero it is required before the user is allowed to calibrate the DPC or manually change the calibration constants IMPORTANT It is recommended that the access password be recorded and filed in a secure location LOCAL OPERATION 4 18 1 The calibration password is set trom the Calibration Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Calibrate F3 2 Press the Access 4 key If there is a password in the system other than 0 then you must enter the current valid password into the 7250sys before it will allow you to modify the password 3 Use the numeric keypad to enter the new calibration password Setting the calibration password to zero allows free access to DPC calibration and constants Press ENTER 4 Press Yes F4 to acknowledge changing the calibration password Press No F5 to reject changing the calibration passwor
22. 2 PACKING 5 7 1 7 3 SHIPPING INSTRUCTIONS 7 2 APPENDIX A SUMMARY OF SPECIFICATIONS UNCERTAINTY 5 1 A2 SPECIFICATIONS A 6 APPENDIX B SUMMARY OF ERROR MESSAGES 1 LIST FIGURES FIGURE 2 15 DPC BLOCK DIAGRAM O 2 FIGURE 2 2 MODEL 7252sys DPC GAUGE PNEUMATICS DIAGRAM 2 4 FIGURE 2 3 PRESSURE CONTROL NORMAL 2 8 FIGURE 2 4 PRESSURE CONTROL FAST 2 9 FIGURE 2 5 SHAFT MAGNET SECTION REOR EN trn SERE rr eta 2 10 FIGURE 2 6 FRIOTOCELL LIGHT SPOT 2 10 FIGURE 4 I MODEL 7252sys FRONT PANEL e enema 4 1 FIGURE MENU TREE dudar beds inet 4 2 FIGURE 6 4 VACUUM NEGATIVE GAUGE CALIBRATION 6 7 FIGURE 6 5 PHOTOCELE LOCATION ne el 6 15 LIST OF TABLES TABLE 2 15 CONVERSION FACTORS waves ERU KB e E Sh PERS 2 3 TABLE 2 2 MANIFOL
23. AUTO MENU 6 Using the numeric keypad enter the values for Start Stop Tolerance Dwell time Max time number of pressure Points up and number of pressure Points down pressing ENTER after each value The rotary knob may be used to skip fields 7 Press Program F1 The program will be generated and the display will show the first step 8 Press the Name F6 key to edit the name of the program See Section 4 6 3 4 for creating a user defined program name 4 6 3 4 Changing the Name of a Program 1 The name of an existing program is changed from the Program Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Program F4 n addition to changing the name of an existing program a new program may be initiated by selecting new and performing the same steps as outlined to change the name of a program 2 Use the rotary knob to highlight the current name For a new program name select new 3 Press Edit FA The program editing screen will appear displaying the first step 4 Press Name F6 4 23 LOCAL OPERATION MENU PROGRAM EDIT NAME MENU Use the lt F4 and gt F5 keys to highlight a character Turn the rotary knob to select the character from the character set To correct a mistake press Clear F4 and return to step 5 Repeat steps 5 and 6 until the name is complete 0 Press Done F6 to store the contents of the scratch
24. Interface UNIT FS Set units to percent of full scale PRES 20 0 Set control setpoint to 20 5 i PRESSTOL Q001 Set control tolerance to 0 001 5 OUTP MODE CONTROL Enter control mode pon E p NIE x Weave J0UU cePlal UNIT SESTSIPERRES 20 07 TOL OUT P MODE CONTROL NA pp Check t Serial Close t return a A E E x Read pressure status until setpoint is reached Ef MEAS Read pressure COND Read status setpoint Se ee x while kbhit he Clhrequest 000 serral MEAS 5TATSOPERTCOND An continue pressure strtod buffer amp status ACTOL Tp 1 Check errors 2 continue if status 0x10 printf Pressure 9 31 pressure if status amp 2 0 break ease eae ae ee eee eee aes Reset 7252 to Measure mode OUTP MODE MEASURE Enter Measure mode REMOTE OPERATION 5 18 write 7000 serial OUTP MODE MEASURE n check errors Reset Serial Intertace 7 close 77 a ae Ne Og ne oye ey check errors display all 7252 error messages return TRUE if any errors were found 7 ee ee ee int check unsigned char status i
25. Primary sensor by pressing the Sensor F6 key until the words Primary is displayed above the calibration coefficients 6 Select Zero F1 Do NOT press the Calibrate button 7 Select the Mechanical Zero F1 key 0 Out of Range 99 Temperature 0 00 Stable 0 Reference 0 000 Stable 0 8 Referring to Figure 6 5 slightly loosen the Allen screw the back of the sensor bracket making sure to maintain a snug fit on the screw Using the T shaped Photocell Centering Tool RIC 7250sys 111 adjust the photocells by placing the tool in the hole in the back of the sensor and turning the tool slightly The screen will show a number of horizontal lines The top yellow bar represents the current zero setting The bottom portion of the bar has a green bar in the center and two red bars on either end If the top yellow bar is over the red bar then mechanical zeroing is required If the yellow bar is over the green bar then no adjustment is required MAINTENANCE 6 14 10 11 Adjusting the photocell will cause the yellow bar to reduce in width You want to adjust the photocell until the yellow line is as thin as possible over the green bar Tighten the Allen screw Often when the Allen screw is tightened the zero will move Review the width of the yellow line again loosen the Allen screw and now offset the yellow bar the same width that you observed it moving trom tightening the Allen screw and now offset it in the opposite d
26. Reference Line and the reference plane of the device under test 3 Press the Unit key found in the keypad and press in mm F1 to select either inches in or millimeters mm for the head height entry 4 The head height is set from the Setup User Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 and then User F2 5 Press Medium F3 to select either Air or Nitrogen The selected units will be highlighted 6 Press Position F4 to select if the position of the Device Under Test is either Above or Below the 7250sys The selected units will be highlighted and appear in the Gas Head description 7 Use the rotary knob to highlight the label Gas Head 9 Use the numeric keypad to enter the height in the selected unit 9 Press ENTER to accept the entry 4 6 1 2 5 Atmosphere The nominal barometric pressure value for the location that the DPC is utilized should be entered for atmosphere On gauge mode instruments this number is used to calculate the density of the test port pressure medium and to correct for head pressure variances between the reference port of the DPC and the DUT 4 6 1 2 6 Pressure Filter is used to adjust the degree to which the front display pressure value is filtered A value of four 4 is the default value As the value increases the filtering level increases however the display update rate reduces Typical filter values would r
27. Reserved 0 Bit3 Reserved 0 Bit4 Measuring The instrument is actively measuring Bit5 Reserved 0 Bit7 gt Reserved 0 Bit8 Self test in progress Bit9 Reserved REMOTE OPERATION 5 10 Bit 10 Bit 11 Bit 12 Bit 13 Bit 14 Bit 15 Reserved 0 Reserved 0 Reserved 0 Reserved 0 Program running Reserved 0 Questionable Status QUES EVENT QUES CONDITION QUES ENABLE BitO Supply voltage questionable Bit Reserved 0 Bit2 Time is questionable Set when the clock has not been set Bit3 Temperature is questionable Sets when oven temperature is not within range Bit4 Reserved 0 Bit5 Reserved 0 Bit6 Reserved 0 Bit7 Calibration is questionable Set when the unit has not been calibrated Bit8 Pressure is questionable Set when the pressure is overranged Bit9 Reserved 0 Bit 10 Reserved 0 Bit 11 Reserved 0 Bit 12 Reserved 0 Bit 13 Reserved 0 Bit 14 Command warning Set whenever a command ignores a parameter Bit 15 Reserved 0 5 5 SERIAL OPERATION The RS 232 port accepts the same SCPI commands as the IEEE 488 port The commands can be terminated by a carriage return hexadecimal OD or a line feed hexadecimal The responses are always terminated by a carriage return followed by a line feed The serial port also supports XON XOFF When the XOFF hexadecimal 13 command is received the DPC will stop transmitting Transmission is restarted when the XON hexadecimal 11 comma
28. are non zero 5 0 for high range sensor s 1 tor low range sensor Range Coefficients KnF O Range Unused 4 Valid High FSR Range 5 Valid Low FSR Range KnO Kn1 Kn2 Calibration constants tor range K 2 K B A 2 13 THEORY OF OPERATION Where A is the zero corrected counts 7 381 975 full scale of current range and 15 the calibrated counts 7 381 975 full scale of current sensor KnH Zero corrected counts for upper limit of range When the zero corrected counts the A D exceed this value the next higher range will be used if possible 7 381 975 full scale of current range KnL Zero corrected counts for lower limit of range When the zero corrected counts from the A D are below this value the next lower range will be used if possible 7 381 975 full scale of current range n Range number 1 4 for high range sensor 5 8 for low range sensor THEORY OF OPERATION 2 14 SECTION 3 0 INSTALLATION 3 1 INTRODUCTION This section of the manual discusses initial installation for the Model 7250 5 DPC Installing the DPC involves connecting the supply and test pressure tubing powering up the unit and contiguring the system through the front panel 3 2 UNPACKING THE DPC Caretully unpack all components checking for obvious signs of damage The shipment contains the following items 1 Model 7250sys 2 power cord 3 user s manual 4 calibration report 5 user specitied instrument
29. completed The DPC should display a screen similar to the one shown below The right hand side of the display should show the options At power up there may be errors relating to the default settings If an error message is displayed in red at the bottom of the screen press F6 then press PREVIOUS If multiple errors exist you will need to press the F6 key multiple times to clear all of the errors MAIN MENU The double sized numbers in the top center of the display shows the current measured pressure 0 00 psi gauge The upper left corner shows the current mode of the DPC MEASURE CONTROL or VENT Below this shows the full scale of the selected pressure range that the system is operating displayed in current units of measure The right side of the screen shows a bar graph displaying the current pressure relative to a user configurable full scale value Below the pressure is the pressure control set point below this is the difference between the set point and the actual value Below this is a numeric scratchpad for entering a new set point value The highlighted label on the right hand side of the screen displays the current assignments of the function keys F1 through F6 that are located beside the display Step 1 Change the pressure units The units are changed by selecting the UNITS key on the keypad LOCAL OPERATION 4 4 kPa kgf cm inHg 0 C inH20 4 C user1 mbar meters Pa Step 2 Step 3 Vacuum _
30. errors display alli GPIB aud 7252 error messages EJ um return TRUE if any errors were found kJ FE M sj Int check errors VOI unsigned char status int retval rr Check Tor GPIB Interface Errore J eee eee a ee ee eee eee x if ibsta amp ERR printf GPIB Status 4X Error d n 21 Check for 7252 Errors retval 0 while kbhit ibrsp device amp status 7 fe Serial porli F Check error bit break retval 1 request 7000 Get error message printf buffer return retval TROP E E E E write 7000 write a command to the 7250 nr Jc t c C ee Li VOLO write 7000 char s ibwrt device s strlen s 5 13 REMOTE OPERATION p cu T EA ele me Peek NET RR Volo gequest 7000 Ghar ibwrt device s strlen s ibrd device buffer sizeof buffer ee ae PE E m LI ON ah M LOL x 5 6 2 SAMPLE PROGRAM 2 7252 GPIB IEEE 488 ZERO SEQUENCE Sample Program 2 7252 GPIB IEEE 488 Ds f Zero Sequence ay n TIC WE x include lt stdio h gt include
31. highest performance values that can be assigned to the system However this uncertainty statement is more difficult to express since it must be expressed for each sensor range in both Percent of Range and Percent of Reading terms Because of the Percent of Range components associated with each sensor the uncertainty of a sensor increases as a percent of reading as the pressure decreases However as the pressure decreases the system switches to a lower range sensor resulting in the uncertainty improving This process repeats throughout the ranges APPENDIX A A 4 of the system The graph below depicts an example of a typical 1000 psi full scale 8 range system maintained on a 1 year calibration cycle The uncertainty of each sensor is plotted resulting in the saw tooth pattern shown The second method is to describe the uncertainty as a Percent of Reading In this example from 3 5 psi to 1000 psi the system maintains an uncertainty level better than 0 01 of Reading as indicated by the horizontal line shown on the graph Below 3 5 psi the maximum uncertainty of the lowest range sensor in the system is 0 00035 psi So the two sigma uncertainty for the system could be expressed as 0 01 of Reading or 0 00035 psi whichever is greater per year This significantly simplifies the uncertainty statement for the system However this method actually downgrades the system performance of the system since it is defining the uncertainty in a worst c
32. lt stdlib h gt include lt string h gt decl h mE Nea M cU D M Im int device GPIB Device descriptor char buffer 256 Buffer for Xnputyoubput Strings 77 double pressure Pressure read from unit status Status register from unit Lie check errors int Zero 6 void write 7000 Char void request 7000 char 59 E a ens a ea ee eee void main void Char sp ee ee x Initialize GPIB Interface Jic cd eh C AME x device ibdev 0 First GPIB Board 4 GPIB Address of 7252 NO SAD No secondary addressing Tis 1 Second Timeout 0 F No automatic BOL for transmit REOS LF Terminate read on Line Feed if ibsta amp ERR cprintf GPIB Driver not installed n return 1010 7 2 ne E if zero REMOTE OPERATION 5 14 ibonl device 0 return YE E E E x Reset GPIB Interface EE E x int zero void ine Estat CLrscr GDrintr Zzeroong s gotoxy 1 5b cprintt Pressure Reading gotoxy 1 6 cprintf Sensor Temperature gotoxy 1 7 cprintf Reference Pre
33. manufacturers calibration uncertainty that was used in the original uncertainty analysis A 1 5 ENVIRONMENTAL OR INSTALLATION INFLUENCES that could cause errors in the transfer standard This includes influences such as ambient temperature line pressure head pressure time response and controller effects It may include other influences that are very specific to one manufacturers instrument It is recommended that the intended application is reviewed to assure that the environmental does not impact the instruments performance or that the impact from the environment is accounted for in the uncertainty analysis For instance if an instrument has a 0 00196FS per degree Celsius temperature effect from a calibrated temperature of 20 degrees Celsius and the instrument is to be used in an environment where the temperature will vary from 15 to 25 degree Celsius then a 0 005 of full scale uncertainty should be included in the uncertainty analysis for ambient temperature effects A 1 6 COMBINING THE UNCERTAINTY COMPONENTS INTO AN EXPANDED UNCERTAINTY STATEMENT Once all of the uncertainty components are identified they can be combined into an overall Expanded Uncertainty Statement for the instrument The vast majority of the measurement community has adopted a statistical approach to uncertainty analysis such as the International Organization tor Standards ISO Guild to the Expression of Uncertainty in Measurement This statistical approach combi
34. number of pressure points required to calibrate the DPC will increase if the range is set up with the a vacuum negative gauge option The screen will display a table noting the following information Step The pressure step in the calibration sequence Apply The pressure that the standard is to generate to the DPC Tolerance The tolerance about the apply value that can be generated by the standard and still accepted by the DPC Actual The actual pressure value that was generated by the standard when the point was accepted Adj FS Depicts the amount that the DPC corrected its output to align to the standard This is used as a trouble shooting tool If one point has a significantly higher adjustment required than other points in the calibration this may indicate that there was an error in that specific calibration point The operator can re check this pressure point prior to completing and accepting the full calibration 2 2 The Step 1 actual value will be highlight This is your first pressure point in the calibration procedure NOTE f the DPC has the Vacuum Negative Gauge Option or the Barometric reference the first two points in the procedure will show the negative pressures that should be generated to calibrate the sensor in the negative gauge direction You are not required to perform both the negative and the positive gauge calibrations every time the unit is calibrated If you want to calibrate only the positive
35. options If necessary report any shipping damage to the freight agency Remove all shipping and packing materials including the shipping plugs from all components If possible save the packing materials tor future shipping needs Finally install the DPC in a location that meets the requirements listed in Table 3 1 Cart versions of the system are supplied with leveling feet Once the cart is rolled into a desired location if the cart is to be maintained in the same location the leveling should be screwed out to secure the cart and level the cart NOTE The DPC should be handled in such a way as to minimize mechanical shocks or vibration during installation or use It should be mounted on a rigid bench or in a sturdy 19 rack Although the zeroing process will compensate for a slightly unlevel mounting the DPC should be mounted to within 5 of level TABLE 3 1 GENERAL SPECIFICATIONS GENERAL PARAMETERS Parameter Model all If there is any condensation when storing the DPC it must be thoroughly dried before power 15 applied It is also recommended to connect the reference port to the test port and evacuating these simultaneously to remove any moisture from the sensor 3 1 INSTALLATION 3 3 CAUTIONS The following cautions should be heeded at all times to ensure safe operation of the DPC 1 Never operate the DPC with the cover removed The power supply has internal voltages near 400 volts 2
36. perform a pneumatic self test the supply port must be connected to a properly set supply pressure and the test port not open to atmosphere For absolute units a vacuum supply must also be connected to the exhaust port 4 6 4 3 Menu Test Remote Test The Menu Test Remote section of the system is used to perform a number of the diagnostic functions on the remote interface t can be used to display the transmitted and received messages that are sent across the interface This can be a powerful tool to assist in identifying the source of communication problems The Menu Test Remote menu displays information from the IEEE 488 interface Pressing the Serial 1 F2 or Serial 2 F3 keys will display information from the serial ports Serial 1 Serial 2 Ints 0 SPoll 00 Status 00 00 MENU TEST REMOTE GPIB MENU 4 6 4 4 Menu Test Shop The Menu Test menu of the system is used to display the current status of the various valve positions in the system This menu is primarily used for diagnostics and will be discussed further in the Maintenance Section 6 0 LOCAL OPERATION 4 28 Test Closed Zero Closed Closed MENU TEST SHOP1 MENU 4 6 4 5 Menu Test Control The Menu Test Control menu of the system is used to tune the controller On new instruments the controller is tuned at the factory and therefore the user should not need to access or make any adjustments
37. stated precision then an error was probably made in generating one of the calibration pressures and the calibration procedure should be repeated Since the system is a multi sensor system it is important to assure that you are reading from the proper system when performing the verification One method to achieve this is 1 From the main screen VENT the system pressure MAINTENANCE 6 6 2 Press the MODE key 3 Press the SENSOR key to toggle between all of the ranges in the system It will start at range A and then switch to B C and so on Please note that all of the sensors in the system are dual scale sensors With the system pressure vented the lower scale of the dual sensor range will be selected As pressure is then applied to this sensor the sensor will automatically switch from the low to the high scale of the sensor when the pressure exceeds the low scale pressure range The selected range will be displayed to the left hand side of the screen in the current unit of measure followed by its range letter designator For example if range A is a 2500 1250 psi scale sensor and you are operating in units of psi the range would be displayed as 1250 0 A Pressing the SENSOR key again it would then display 300 0 B if Range B in the system is a 600 300 psi scale sensor Assure that the sensor range that you want to verity is selected 4 Generate pressures to verify the calibration of the dual scale sensor 6 4 2 VACUUM NEGATIVE G
38. the DPC 4 6 3 MENU PROGRAM STORING A SEQUENCE IN MEMORY A program can be run on only the one selected channel at a time Consider an exercise that requires the DPC to start at 30 psi increase to 50 psi then decrease to 20 psi Test sequences like this may be stored in the DPC s memory as a program One benefit of storing a sequence in memory is that the user does not have to command each pressure separately every time a multipoint test or calibration routine is performed Another benefit is that the user can specify a tolerance for each set point pressure Once a tolerance is set the dwell timer will start counting down instead of waiting until the pressure is at the exact set point to start the dwell timer This gives the user a time advantage compared to manual mode operation and provides a degree of automation without the use of an external computer 4 19 LOCAL OPERATION The DPC can store up to 1 000 program steps that may be divided among a maximum of 20 named programs The Program menu operates only on the current channel The other channel will be in measure mode while the program is running 4 6 3 1 Preparing to Program Before entering a test sequence consider the items discussed below Program Name Valid program names range from one to eight characters in length and can include numbers upper case letters and the and symbols For example Exer 14 and FStest are both valid names Configuration Since a pr
39. the pressure source from the Reference Port VACUUM SENSOR CALIBRATION OPTIONAL CASE REFERENCE SENSOR correction can be applied to the vacuum sensor This correction is done using the DPC software and can be performed without removing the vacuum sensor from the DPC chassis 2 10 Place the DPC in Measure mode Remove all pressure sources from the system The Vacuum sensors are located inside the black sensor oven assembly Connect a pressure standard physically as close to the vacuum sensor as possible You may wish to remove the top cover of the instrument and connect directly to the pressure ports going into the quartz sensor oven assembly Note on the 7250sys each sensor will have its own independent vacuum sensor desired change the DPC s units of measure see Section 4 to match those of the calibration standard To access the Calibration screen from the Main Menu select MENU CALIBRATE CALIBRATE Select the atmospheric sensor by pressing the Sensor F6 key until the words Vacuum Sensor or B etc is displayed above the calibration coefficients To begin the calibration process press CALIBRATE the calibration access code is enabled enter it at the prompt The first Calibration screen will appear You will use the calibration standard to apply the two vacuum points on the vacuum sensor The Actual value will be highlighted This is your first pressure point in the calibration procedu
40. to the controller using this menu This menu is user accessible in order to provide a means to set up the controller when control valves are replaced or to perform maintenance on the controller This menu is primarily used for diagnostics and repair and will be discussed further in the Maintenance Section 6 0 AutoTune Full Calibrate MENU TEST CONTROLLER MENU 4 6 5 MENU DISPLAY The Menu Display is used to conveniently monitor most of the sensor output parameters It is primarily used for troubleshooting This display screen shows all available sensor readings from both channels 4 29 LOCAL OPERATION MENU DISPLAY MENU 4 6 5 1 Menu Display Temperature The Menu Display Temp is used to monitor the temperature of each dual range sensor It is primarily used to assist in determining when the sensors in the system are thermally stabilized 4 6 5 2 Menu Display Vacuum The Menu Display Vac is used to monitor the vacuum sensors each dual range sensor that are supplied with the absolute with evacuated reference option lt is primarily used for troubleshooting 4 6 5 3 Menu Display Blank This is used as a screen saver in the 7250sys LOCAL OPERATION 4 30 THIS PAGE INTENTIONALLY LEFT BLANK 4 31 LOCAL OPERATION SECTION 5 0 REMOTE OPERATION 5 1 CAPABILITIES The DPC can be operated remotely by a computer Two interfaces are supported IEEE 488 and RS 232 Both interfaces supp
41. 0sys 2 5 5 PID CONTROL The outer loop pressure controller is a form of PID control executed every 100 milliseconds 10 times per second The pressure is controlled to an exponential decay curve TEENS s p S A i S Atte d 5 4 S Set point A Actual V Control Output p id Control Coefficients Figures 2 3 and 2 4 show typical Control mode operation Pressure in percent of full scale is plotted versus time to show the change in pressure as the instrument steps from one control point to the next pressure Time seconds FIGURE 2 3 PRESSURE CONTROL NORMAL MODE THEORY OF OPERATION 2 8 pressure 0 10 20 30 40 50 60 Time seconds FIGURE 2 4 PRESSURE CONTROL FAST MODE 2 6 TRANSDUCER MODULE 2 6 1 QUARTZ BOURDON TUBE SENSOR TRANSDUCERO1 The quartz Bourdon tube sensor is mounted in a machined aluminum housing The sensor consists of a helical quartz tube with a mirror affixed to one end as shown in Figure 2 5 A rigid beam is attached transverse to the axis of the helical tube Attached to both ends of this beam are electromagnetic coils Mounted beneath the coils are permanent magnets A lamp assembly directs light through a quartz or sapphire window onto the mirror affixed to the helical tube as shown in Figure 2 6 The mirror reflects the light back through the window and strikes two matching photodiodes When there is zero pressure differential across the helical tube the photod
42. 993 kPa and then turn off After a few cycles the system will thermally stabilize and the pressure will hold between the Control On and Control Off Bands 4 6 1 1 5 Control The DPC has two control modes of operation Normal and Fast In the Normal mode minimizing pressure overshooting takes precedence over control speed In the Fast Mode control speed takes precedence over overshooting the commanded set point 4 6 1 1 6 Supply Correction The control performance of the 7250sys is optimized when the fully supply pressure is provided to each of the controller ranges in the system When inadequate supply pressure is present the control performance will suffer When the Supply Correction function is turned on the system adjusts the control parameters to improve the control when it detects insufficient supply pressure LOCAL OPERATION 4 12 4 6 1 1 7 Slew Rate User defined maximum pressure rate of change The DPC is designed to control with minimum overshoot into a wide variety of external volumes at its highest slew rate Therefore in most applications it is recommended that the slew rate be set at its maximum rate value This provides the highest speed control without jeopardizing overshoot or control stability properties The only application where the operator may wish to slow down the slew rate control speed is in applications where the device under test could be damaged by high rate of pressure change The DPC control algorithm t
43. ACE dac oic ates 2 3 2 23 29 RO CAINE LI 2 3 2 4 PNEUMATICS MODULE 2 4 2 4 1 MEASURE 5 229 2 4 2 5 2 4 1 1 1 Barometric Sensor uiui etri 2 5 2 4 1 1 2 Absolute with Evacuated Reference Optional 2 5 2A 2 6 1 3 Procedure 2 6 2 4 2 CONTROL MODE 2 6 2 4 2 Pressure SUPPI PO et E 2 6 2 4 2 2 Vacuum Supply Exhaust 2 6 24422 32 Pressure COD Ol pda 2 7 25 CONTROL STRATEGY 22 2 7 2 5 ou siete tet 2 7 2 22 oe ep lota te 2 7 im 2 7 2 5 4 ALIGNMENT OF INNER LOOP WITH OUTER LOOP 2 8 PDC CONS Re ETE 2 8 2 6 TRANSDUCER MODULE 2 9 2 6 1 QUARTZ BOURDON TUBE SENSOR TRANSDUCERO1 2 9 2 60 2 SENSOR BOARD 2 10 INT
44. AUGE CALIBRATIONS Vacuum mode is an available option The following configuration should be used when calibrating in the Vacuum mode METERING VALVE CUTOFF VALVE L g 1 REFERENCE DEADWEIGHT GAUGE gt DPC inn eee QS OX PRESSURE CONTROLLER REF VACUUM SYSTEM PRESSURE amp VACUUM FIGURE 6 4 VACUUM Negative Gauge CALIBRATION 6 7 MAINTENANCE To calibrate in Vacuum mode with the configuration shown in Figure 6 4 the following actions should be taken The system pressure and vacuum inlet valve should remain closed The bottom side of the piston must be open vented to atmosphere and connected to the reference port of the DUT The test port of the DUT must be connected to the bell jar with a cutoff valve to isolate it from the DUT Additionally there must be a cutoff valve located between the Vacuum pump and the bell jar Close the Cut off valve to isolate the DUT test port from the bell jar Open the Vacuum Pump Valve to pull a hard vacuum on the bell jar to seal the bell jar and to float the masses Once the masses have risen in response to evacuation of the bell jar close the reference vacuum pump cutoff valve Use the metering valve on the bell jar to adju
45. D SOLENOID VALVE 2 5 TABLE 3 1 GENERAL SPECIFICATIONS GENERAL 5 3 1 ELECTRONICS SELF TEST 6 2 TABLE 1 PERFORMANCE 85 nnne A 6 1 INTRODUCTION SECTION 1 0 GENERAL INFORMATION 1 1 INTRODUCTION This manual contains operation and routine and preventive maintenance instructions for the Model 7250sys Digital Pressure Control System DPC manufactured by GE Ruska Houston Texas This section of the manual provides general information about the DPC and presents its features and options 1 2 GENERAL INFORMATION The GE Ruska Model 7250sys DPC uses force balanced fused quartz Bourdon tube technology to provide the precise measurement of pressure During normal operation the DPC performs in either Measure mode or Control mode In Control mode the DPC simultaneously measures and controls pressure Control mode is commonly used in the calibration and testing of pressure gauges transducers pressure switches and production pressure instruments In Measure mode the DPC measures pressure Typically Measure mode applications are found in research laboratories wind tunnel testing power plant testing and bubbler tank volume accountancy systems It is also used to monitor barometric pressures vacuum systems and differential pressure devices
46. E SUPPLY PORT Each individual control channel internal to the system has its own individual pressure supply port which must be connected to an independently regulated source of clean dry nitrogen or air Shop air should not be used Refer to Appendix A for supply port gas purity and pressure regulation requirements The integrated cart version of the system has an integrated regulator panel which supplies the proper pressure to each of the control channels On these cart systems a single regulated pressure source supplies the entire cart INSTALLATION 3 2 On the table top version of the system each control channel will require individual regulated supply pressures It is important to assure that each control channel is supplied with the proper regulated pressure Each channel will be labeled with the pressure that it should be supplied Tubing must be of at least 1 8 inch 3 mm inside diameter and of a sufficient wall thickness for the pressure Either stainless steel or copper tubing is acceptable 3 5 2 EXHAUST PORT On a cart system the exhaust port is an port internal to the system These are ports that the controllers vent pressure when in control mode If the system is purchased with the internal vacuum supply pump the control channels that require the vacuum supply pump to control sub atmospheric pressures will be connected to this pump On the table top systems the exhaust port may be left open to atmosphere under most conditions
47. ERATION 5 8 control band set control mode 1 FAST O NORMAL set list of pressure values number of points defined specifies dwell times number of dwell times specifies tolerances number of tolerances direction to go through list number of times to go through list read clear operation event register read operation condition register set operation enable mask read clear questionable event register read questionable condition register set questionable enable mask clear enable masks Freq ignored system date returns lt error descr info gt or Error keyboard lock system time SCPI protocol version returns 1991 0 set interface emulation reset pressure control 0 No ELECtronic Run Elec Self Test amp Return Result PNEumatic Start Pneu Self Test PNEumatic Get Pneu Test Results STOP Abort Pneu Volume or Leak UNIT DEFine n name number Create Unit LENGth EX PE T G MA K M U NIP F A M FT IN set length units PRESsure name set pressure units TEMPerature set temperature units LENGth lt name gt set length units head height 5 4 5 EXAMPLE SCPI COMMANDS To request the current pressure reading all of the following commands are equivalent MEASURE PRESSURE measure pressure MeASUrFE pReSsUrE meas pres measure meas MEAS To set the control pressure setpoint to 50 all of the following commands are equivalent SOURCE
48. Feed if ibsta amp ERR prinbt GPIB Drivet nob return x inztrallize 125 Intertdce n 4 m UNIT 986 Set units to percent of full scale as PRES 20 0 Set control setpoint to 20 5 PRES LOL 0 001 Set control tolerance to 0 001 FS OUTP MODE CONTROL Enter control mode na En x 7000 UNIT RS PRES 20 07 TON 0 001 00TE MODE CONTROL gt errors 4207 ibonl device 0 IN te x Read pressure status until setpoint is reached des es MEAS Read pressure 22 Read status setpoint Na Nl POR while kbhit t Bequest 7000 pressure strtod buffer amp status atoi p Check errors vo REMOTE OPERATION 5 12 continue if status Ox10 printf Pressure 9 31 pressure if status amp 2 0 break ee ae Reset 7252 to Measure mode 7 JE OUTP MODE MEASURE Enter Measure mode Pa ae d ic Ac cA c AS LU E x write 7000 OUTP MODE MEASURE n CHECK Crrors u Reset GPIB Interface ore eee x ibonl device 0 Se N E E check
49. Jog function Please see Section 4 5 4 3 2 ENTERING EXITING CONTROL MODE 1 The Control mode is set from the Main Menu Press PREVIOUS until the Main Menu appears 2 Press CONTROL F2 to enter Control mode ENTER must be pressed to contirm entry into Control mode Note that any entry in the numeric scratchpad will also be taken as the new pressure set point On DPC s with full scale pressure ranges less than 1000 psi 6 9 MPa the DPC controls its internal pressure to the test port pressure before opening the isolation valve and entering the Control mode During this period the Control mode indicator flashes 3 Press MEASURE key found in the keypad to exit Control mode No confirmation IS necessary 4 3 3 ABSOLUTE ZERO OF DEVICE UNDER TEST OPTION Some systems are configured with an option that allows the system to pull a hard vacuum on the DUT Device Under Test to aid in zeroing the DUT With the system operating the absolute mode and in control mode when a set point of is entered the system will control down to the lower limit of the controller The controller will then be placed in the measure mode A 3 way valve then switches to tie the test port of the system directly to the vacuum pump and isolate the remaining section of the system from the test port This allows the vacuum pump LOCAL OPERATION 4 8 to pull a hard vacuum to the DUT A vacuum sensor is tied to this evacuated line and its reading is displa
50. MaxTime The max time is the maximum time in seconds including the dwell time that the DPC can spend on one step of the program the max time elapses the DPC will automatically proceed to the next set point in the program even if the current set point has not been achieved Thus the max time selection limits the amount of time that the DPC can spend on any one set point Typically the max time should be set to a value greater than the dwell time If the max time is set to zero the DPC will attempt to achieve the set point indefinitely i e the max time function is disabled Mode of Entry If the upscale portion of the desired pressure step sequence and the downscale portion of the sequence both have the same highest and lowest set points and consist of evenly spaced steps the Auto option can be used to automatically generate the program However if any part of the sequence includes unevenly spaced steps or the starting and ending set points are not the same each step must be programmed individually In the example given at the beginning of Section 4 6 3 each step must be LOCAL OPERATION 4 20 programmed individually since the starting set point is 30 psi and the ending set point is 20 psi Detailed instructions for entering these items are given in the sections that follow 4 6 3 2 Entering a New Program To program the DPC use the keys on the panel to change values on the DPC s program editing screen Instru
51. NAB STAT QUES ENAB The Service Request Enable Register SRE is used to generate service requests on the IEEE 488 bus If a user sets a bit in this register when the instruments sets the corresponding bit in the Status Byte Register STB a service request is generated SRE Status Byte Register STB Service Request Enable Register SRE Bit7 Operation status summary Set when an event enabled in OPER ENABLE occurs Bit6 Service request Set when an event enabled in SRE occurs This bit is not used in SRE Bit5 Event status bit Set when an event enabled in ESE occurs Bit4 Message available Set when a response is ready to be sent Bit3 Questionable status summary Set when an event enabled in QUES ENABLE occurs Error event queue not empty Bit 1 Reserved 0 BitO Reserved 0 Standard Event Status Register ESR Standard Event Status Enable Register ESE Bit 7 Power on Set at power up Bit6 Reserved 0 Bit 5 Command error Error in command syntax Bit4 Execution error Error in command execution Bit3 Device dependent error Device error independent of commands Bit2 Query error Output queue empty when request received Bit Reserved 0 Operation complete Set for DPC command Operation Status OPER EVENT OPER CONDITION OPER ENABLE BitO Calibrating Currently performing a calibration Bit Settling Control setpoint has not been reached Pressure tolerance set by SOUR PRES TOL Bit2
52. NT function key as the pressure set point Note you can use the vent as a set point at any point in the program The dwell and max time function with vent just as they would at a controlled set point 9 When all steps have been entered press PREVIOUS to return to the Named programs screen See Section 4 6 3 4 for creating a user defined program name 4 6 3 3 Automatically Generating a Program For the DPC to automatically generate a program the user must input the first set point pressure the last set point pressure and the number of steps in between as well as the dwell time max time and tolerance common to all set points 1 Ensure that the units limits and control parameters are set to their desired values 2 The program is entered from the Program Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Program FA 3 Use the rotary knob to highlight new If these steps are used on an existing program all program steps will be deleted and replaced with the automatically generated program 4 Press Edit F4 Since new was highlighted the DPC will create a new program and give a default name of NAMEnn where nn is a two digit number The program editing screen will appear displaying the first step 5 Press Auto F3 LOCAL OPERATION 4 22 Program Dwell Time Max Time Points Up Points Down MENU PROGRAM EDIT
53. OFF 5 1 REMOTE OPERATION The RS 232 connection is a DB 9P connector found on the back panel of the DPC It is located on the processor board The following pins are used all other pins are reserved Pin Direction Signal 2 In RXD Receive Data 3 Out TXD Transmit Data 5 GND Ground 7 Out RTS Request to Send 5 2 REMOTE LOCAL OPERATION In Local mode the DPC is operated manually through the front panel Section 4 0 covers local operation The DPC always powers up in the Local mode In Remote mode the DPC is operated by a computer connected to an interface Most functions that can be performed in Local mode can also be performed remotely Remote mode does not automatically disable local operation The remote interface may be active while local operations are being done In cases where full remote control is required the following methods may be used 1 Issue a Local Lockout LLO interface message via the IEEE 488 interface The DPC will disable the local keyboard until the Go To Local GTL interface message Is received or the REN Remote Enable line is unasserted This method cannot be used on the serial interface 2 Issue the SCPI command SYSTEM KLOCK ON to lock the local keyboard The DPC will disable the local keyboard until the command SYSTEM KLOCK OFF is received 3 Issue the 5 command DISPLAY ENABLE OFF or DISPLAY TEXT lt string gt These commands will disable the local display in addition to locking the ke
54. PRESSURE LEVEL IMMEDIATE AMPLITUDE 50 SOUR PRES LEV IMM AMPL 50 0 PRESSURE 50 PRES 50 To zero the unit via the remote interface use the following sequence CAL ZERO INIT Enter Zero Mode CAL ZERO INIT Read Status Mode Pressure Temperature Reference and Wait Until Stable CAL ZERO RUN Start Zero Adjust Sequence STAT OPER COND Wait Until Complete Bit O O 5 4 6 5 STATUS REGISTERS Three type of status registers are available Condition Event and Enable Condition registers always show the current status of the instrument Bits may turn on and back off between reads The status read is the status of instrument at the moment of the read Condition registers include STB Status Byte Register ESR Standard Event Status Register STAT OPER COND Operation Status Condition Register STAT QUES COND2 Questionable status Condition Register 2 9 REMOTE OPERATION Event registers do not show the current state but flag the bits in the condition registers that have changed since the last time the event register was read When an event register is read it is reset to zero STAT OPER EVENT Operation Status Event Register STAT QUES EVENT Questionable Status Event Register Enable registers are set by the user to create summary bits If the user sets a bit in the enable register when the instrument sets the corresponding bit in the event register a summary bit in the Status Byte Register 15 set ESE STAT OPER E
55. Py L OTOCELLS G RATE VOLTAG 58 e ET d __ 7 ACCORDING ILLUMINATION M BETWEEN PHOTOCELLS gt POTENTIOMETER FOR ZERO ADJUST BEAM OF LIGHT E c REFLECTED FROM JJ CALIBRATION E QE E ROTATING MIRROR MIRROR ERROR SIGNAL TO CONTROL AMPLIFIER 15 Tr ZERO WHEN PHOTOCELLS ARE EQUALLY A LLUMINATED ROTATING AXIS FIGURE 2 6 PHOTOCELL LIGHT SPOT 2 6 2 SENSOR BOARD A temperature sensor and the quartz Bourdon tube pressure sensor are monitored by the Sensor Board The Sensor board is also used to control and maintain the sensor housing at 50 C 2 6 3 LINEARIZATION TERM As described in the previous section the relationship between the pressure being measured and the current required to keep the quartz Bourdon tube in its zero position is the main principle behind the operation of the DPC s sensing element Ideally this pressure current relationship would be a linear equation of the form I where is current k is a constant of proportionality and P is pressure However due to certain mechanical characteristics of the helical tube and its supporting structure this THEORY OF OPERATION 2 10 pressure current relationship is slightly nonlinear The nonlinear portion of this pressure current relationship closely follows the form of a second order polynomial or I 2 aP where again P is pressure and a b and c ar
56. RODUCTION 2 7 3 1 3 2 3 3 3 4 3 5 4 1 4 2 4 3 4 4 4 5 4 6 2 0 9 LNEARIZA HON TER 2 10 2 61 AUXILIARY SENSORS e 2 11 2 6 4 1 Case Reference Vacuum Sensor Option 2 11 SOFTWARE 2 11 2 CONTROLS 2 11 2 7 1 1 Preventing Operator Errors 2 11 Zla 2 11 2 12 COVE 2 12 2 7 1 5 Pressure Reading and Correction 2 13 SECTION 3 0 INSTALLATION INTRODUCTION 3 1 UNPACKING THE DPC 3 1 CAUTIONS 3 2 POWERING UP THE 3 2 3 4 1 OBSERVING THE DPC S FULL SCALE RATING 3 2 PNEUMATIC 65 3 2 2201 PRESSURE SUPPLY POR Trenaren 3 2 32942 3 3 eo ME EPOR 3 3 REFERENCE POI tad 3 3 3 5 5 VACUUM SENSOR 3 4 SECTION 4 0 LOCAL OPERATION TUTORIAL 44 4 3 d 12 SEBECTINO LANGUAGE ee db
57. Setup Remote The Menu Setup Remote screen is where the remote communication interface is set Up LOCAL OPERATION 4 16 Default 4 6000 510 1200 2400 988 19200 5 1402 MENU SETUP REMOTE MENU 4 6 1 4 1 GPIB Address Sets the IEEE 488 interface address 4 6 1 4 2 Protocol The Protocol defines which protocol should be used by the remote interface The options are Standard Communication for Programmable Instruments SCPI which is the only interface available for the 7250sys 4 6 1 4 3 Serial Interface Set Up The operator can set up the Baud Rate Data Bits Parity and Stop Bits for the Serial Interface 4 6 1 5 Menu Setup System The System Menu identities the Software release version that is being operated in the DPC It also stores and allows the operator to edit the Date and Time Ruska Instrument Model 1250 Software Version 2002 09 06 10 49 32 2002 09 11 19 55 SD MENU SETUP SYSTEM MENU 4 6 1 5 1 Date Time The DPC s system clock is continuously updated If the date or time requires editing the following applies 4 17 LOCAL OPERATION 1 The date and time are set from the Setup System Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 and then System F5 2 To set the system date turn the rotary knob until Date is highlighted Use the numeric keypad to enter the curren
58. T CONTROL MENU MAINTENANCE 6 16 NOTE Be sure the Control Band parameter is set to zero Section 4 6 1 1 3 If the controller does not control optimally it would be recommended to first assure that the system is free of leaks and is operating within the external volume specifications see Appendix A You should verity that the instrument is fitted with the proper sized pressure lines to minimize flow restrictions see Section 3 5 Verify that the control band is set as intended see Section 4 6 1 1 3 For active control when testing the controller the Control Band Off and Control Band On values should be set to zero Finally verity that the control is set to Normal to minimum overshoot see Section 4 6 1 1 4 If the system continues to control improperly you can pertorm the Auto tune There are two options available to the operator Full This fully characterizes the control function of the 7250sys It automatically adjust the control valve biases and aligns the inner loop high control pressure sensor to the high accuracy quartz sensor This should be performed any time major components are replaced in the controller such as the control valves or the high speed inner loop control sensor Additionally if the controller is not functioning properly a full Auto tune can be performed to optimize the control Calibrate This automatically aligns the inner loop high control pressure sensor to the high accuracy quartz sensor If in
59. The standard DPC requires a positive pressure calibration A vacuum negative gauge option is available and requires special calibration per Section 6 4 2 No disassembly is required and there are no potentiometers to tune NOTE The uncertainty of the final calibration must include the uncertainty of the pressure standard being used 6 4 1 1 Preparation 1 Verify that the DPC s Reference Port is open to atmosphere for gauge calibrations and that the calibration standard is connected to the Test Port 6 3 MAINTENANCE 2 For DPC s with pressure ranges greater than 100 psi 690 kPa verify that the supply pressure port is plugged or a supply pressure is connected to the supply port and adjusted to 110 of the full scale of the DPC 3 Verity that the DPC has been at stable environmental temperature and that each sensor s oven temperature MENU DISPLAY TEMPERATURE are stable to 50 degree Celsius The typical warm up time is 3 hours 4 Verity that the DPC is in Measure mode Section 4 0 5 desired change DPC s units of measure Section 4 0 to match those of the calibration standard 6 Set the gas head to 0 Select MENU SETUP USER 7 To access the calibration screen select MENU CALIBRATE CALIBRATE Primary 110 00 psi 2 2 Calibrate COL 288 260 502 0 0000176 12870 K10 328 K11 0 0000200 K12 344 Last Zero 0000 00 00 00 00 00 Last Calibrate 0000 00 00 00 00 00 Sensor
60. VALue n POINtS DATE TIME ZERO DATE TIME Sensor A Sensor B Sensor C Sensor D Sensor E Sensor F Perform calibration point return number of calibration constants returns label value 0 0 123 sets calibration constant return nominal calibration point return number of calibration points last calibration date last calibration time last zero date last zero time REMOTE OPERATION VALue number sets vacuum value microns mtorr INITiate enter zero calibration mode INITiate returns status for cal press temp ref start zero calibration STOP abort zero calibration The next section of calibration commands are valid for the following auxliary sensors PRESsure2 Sensor A Case Reference PRESSsure12 Sensor B Case Reference PRESsure22 Sensor C Case Reference PRESSure32 Sensor D Case Reference PRESsure42 Sensor E Case Reference PRESsure52 Sensor F Case Reference PRESsure3 Sensor RPT PRESsure4 Controller A PDCR PRESsure14 Controller B PDCR PRESsure24 Controller C PDCR VACuum Sensor A Vacuum VACuum1 1 Sensor B Vacuum VACuum21 Sensor C Vacuum VACuum31 Sensor D Vacuum VACuum41 Sensor E Vacuum 51 2 Sensor F Vacuum 2 Sensor Gas Temperature TEMPerature11 Sensor B Gas Temperature TEMPerature21 Sensor C Gas Temperature TEMPerature31 Sensor D Gas Temperature TEMPerature41 Sensor E Gas Temperature TEMPerature51 Sens
61. Vacuum _ psi cmHg 0 C 20 4 25 C atm feet km hr MPa cmHg 0 C cmH20 4 C 25 C atm feet km hr mmHg 0 C inHg 60 F 20 C 2 5 knots hPa kgf cm inHg 0 C inH20 4 C user1 mbar meters Pa UNITS MENU Use the rotary knob located to the right of the display to move the highlight bar to the desired unit Note the highlighted curser initially shows the current unit of measure When the rotary knob is moved the current unit remains highlighted in a gray color and the new unit is highlighted in a light blue color When the unit desired is highlighted press the ENTER key on the far right side of the front panel under the numeric keypad The display will return to the MAIN screen with the current units inHg 60 F 20 C user2 FS knots hPa The second part of this tutorial uses the DPC to generate pressure The pressure supply must be connected and the test port must be connected to a closed volume in accordance with Section 3 5 of this manual Step 4 From the Main Menu use the numeric keypad to enter the starting pressure The pressure 15 entered in the units set in the previous exercise As the pressure is entered each digit will be displayed in the numeric scratchpad the highlighted box in the lower section of the display If a mistake is made press the CLEAR key found in the numeric keypad and the numeric scratch
62. andard DPC is fully functional with just these items and the appropriate pressure and vacuum supplies the following options are also available NVLAP Accredited Calibrations GE Ruska received formal accreditation from the National Voluntary Laboratory Accreditation Program NVLAP which is administrated by the National Institute of Standards and Technology NIST NVLAP has assigned GE Ruska laboratory code 200491 0 to indicate that our accredited calibration services are in compliance with all relevant requirements of ISO IEC 17025 1999 and ISO 9002 1994 GE Ruska s calibration laboratory can provide an optional accredited pressure calibration The NVLAP calibration certifications are optional and must be requested at time of order 1 3 INTRODUCTION NOTES INTRODUCTION 1 4 SECTION 2 0 THEORY OF OPERATION 2 1 INTRODUCTION The DPC s power supply electronics pneumatics and sensor combine to form a complete stand alone measure and control system This section of the manual describes the DPC s component modules Figure 2 1 and provides a general discussion TEST 2 6 2 of each ducc cM C Gc CM ELI X QE MI oce Uu c EEUU CES Primary Dual Range Transducer Module A I Ref REF SENSOR Photo SENSOR e suu Section Sensor BOARD 2 6 1 Section gt Exhaust Section 2 4 Pneumatics Dak ee Lc c c
63. ange between 1 to 10 For pressure sensors with full scale ranges of 1 psi 7 kPa or less a filter value up to 30 is typically recommended LOCAL OPERATION 4 14 4 6 1 2 7 Changing the Number of Decimals Each unit has default number of decimal places used for pressure display This may be adjusted up or down by one decimal place 1 The decimal digits are set trom the Setup User Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 and then User F2 2 Turn the rotary knob until the label Display digits is highlighted 3 Turn the rotary knob further until the desired number of digits from the default resolution is highlighted 1 O 1 and then press the ENTER key to select 4 6 1 2 8 Key Click The DPC can be configured to emit a clicking sound each time a key is pressed 1 The key click is set from the Setup User Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 and then User F2 2 Turn the rotary knob to highlight Key click and then highlight either on or off 3 Press the ENTER key to select 4 6 1 3 Menu Setup Units In addition to the standard units of measure provided by the DPC four user defined units are available To create a user defined unit the user enters a name that is one to ten characters long and a conversion factor that is a multiple of kiloPascals kPa For exa
64. ange primary transducer modules 12 range 7250sys system incorporates a Primary Module C in addition to the hardware denoted in Figure 2 1 This module would contain the Pneumatic Module C and the dual range transducer modules E and F and would be connected into the system as the Primary Module B is connected 2 2 POWER SUPPLY The DPC s universal power supply accepts AC voltages 90 to 260 volts at 47 63 Hz and DC voltages trom 100 to 370 volts This quad output supply produces 5 VDC 12 VDC and 24 VDC which are distributed to the Control and Backplane Boards 2 3 ELECTRONICS MODULE 2 3 1 BACK PLANE BOARD The Back plane Board is used to interconnect all of the plug in electronic boards and distribute power The Microprocessor Board the Digital Control Board and the 488 Interface all plug into the Back plane Board The Front Panel communicates with the Microprocessor Board via cables Sensor Board communicates with the Microprocessor board through an internal RS 485 serial communication bus 2 3 2 MICROPROCESSOR BOARD All of the DPC s software resides in nonvolatile programmable read only memory Flash EPROM on the Microprocessor Board which plugs directly into the Back plane Board This software contains all of the instructions that operate the DPC as well as the conversion factors that the DPC uses to translate the internal pressure unit of measure of kPa into the units selected by the user These
65. are correct MAINTENANCE 6 10 NOTE In addition to saving the calibration coefficients to the DPC s memory separately record the calibration coefficients and store this backup in a safe place 8 To exit the editing procedure without storing the calibration coefficients in memory press CANCEL To store the calibration coefficients in memory select DONE F6 9 Press PREVIOUS to return to the Main Menu Once the calibration coefficients are input the user should record several pressure readings If there are any variances beyond the stated precision at these points then the calibration procedure should be performed 6 4 6 ZEROING The zeroing procedure is performed to correct for system zero shift and does not require a full calibration The most important requirement for performing a valid zeroing procedure is to guarantee that there is not a pressure differential between the sensor s test port and case reference If during the zeroing procedure the message Mechanical Zeroing Needed appears the sensor photocell may need to be zeroed See Section 6 5 for more information The zeroing screen presents several pieces of information The screen will display the current status of the pressure sensor Stability and Temperature If any of the above are unstable then the system will delay until stability is achieved Pressing OK F6 will bypass this wait period NOTE Bypassing this wait period can have a negative ef
66. ase scenario Either method is appropriate It is recommended to select a method that best meets an individuals requirement 1000 psi Full Scale 8 Range System Two Sigma Uncertainty per year 0 0110 0 01 of Reading 0 0105 0 0100 0 0095 0 0090 Uncertainty 0 0085 0 0080 0 0075 1 10 100 1000 Pressure psi A 5 APPENDIX A 2 SPECIFICATIONS GENERAL SPECIFICATIONS Available Pressure Range Display Display Resolution Electrical Power Operating Temperature Storage Temperature Humidity Nominal Control Volume Standard Pressure Units Pneumatic Ports Relief Valves Supply Pressure PERFORMANCE Minimum to 1000 0 to 70 bar Maximum 0 to 2500 psi 0 to 170 bar 6 4 inch TFT Active Matrix Color User selectable up to 1 1 000 000 90 260 47 63 Hz 50 400 Hz for i xi models 150 18 36 20 70 5 95 relative humidity non condensing 5 60 80 1000 5 inHg at O C and 60 F kPa bar psi inH O at 4 C 20 and 25 C kg cm mmHg at 0 C cmHg at 0 C and cmH O at 4 C inch NPT female Test Port 120 of Maximum Scaled Quartz Sensor Range Reference 10 where applicable 115 FS for units greater than 100 psi of each channel 100 FS plus 15 psi for units less than or equal to 100 psi for each channel TABLE A 1 PERFORMANCE SPECIFICATIONS 7250sys lt 0 34bar 0 34 172 bar
67. ation Program Test and Display functions 4 9 LOCAL OPERATION 1 as Calibrate Program Display MENU 4 6 1 MENU SETUP Setup is used to contigure the system It includes setting all of the limits user parameters user defined units of measure remote interface and system setup On the 7250 the User and Limits screens are separate tor each channel and must be set up independently The Units Remote and System screens are identical in each channel Any changes made in one channel immediate affects the other channel MENU SETUP MENU 4 6 1 1 Menu Setup Limits The Menu Setup Limits menu is used to setup all of the limits in the system The pressure limits can be used to protect the device under test DUT from overpressure limits are defined separately for each channel Press the Mode key to switch between two pressure channels The Access code is common and 15 used for both channels LOCAL OPERATION 4 10 110 00 psi Low Limit 20 31 Auto Vent 400 00 Control On Band 0 00 Control Off Band 0 00 Default Control Fast Slew Rate 10000 psi Slew Limit 10000 Access MENU SETUP LIMITS MENU 4 6 1 1 1 High Limit User defined Maximum pressure limit This is often set just over the full scale pressure of the device under test DUT in order to protect the DUT The DPC will then prevent the pressure from e
68. ation Mode The Calibrate button must be pressed before SCPI calibration commands can be executed Pressure Too High 800 Solenoid Over Temperature The control solenoids have over heated Wait until they have cooled before entering Control mode Error reading Barometric RPT Pressure Sensor 802 Control Sensor out of range Controller Communication Error 804 Autotune Failed 38 40 42 45 01 707 801 802 803 804 APPENDIX 2
69. ation access code is enabled enter it at the prompt The first Calibration screen will appear 7 You will use the calibration standard to apply the various pressures that will be requested by the 7250sys The screen will display a table noting the following information d Step the pressure step in the calibration sequence b Apply The pressure that the standard is to generate to the DPC c Actual The actual pressure value that was generated by the standard when the point was accepted 8 The Actual value will be highlighted This is your first pressure point in the calibration procedure This calibration requires the generation of two pressures MAINTENANCE 6 8 10 11 12 6 4 4 A span within the range of 700 to 1100 mbar absolute The selected pressures should be spaced as far apart as possible within the allowable range Generate the first pressure Enter the actual value of the applied pressure generated by the standard and press ENTER Generate the second pressure Enter the actual value of the applied pressure generated by the standard and press ENTER The RPT sensor is now linearly compensated Once the calibration procedure is complete the user should verify several pressure readings against the pressure standard If there are variances beyond the stated precision then an error was probably made in generating one of the calibration pressures and the calibration procedure should be repeated Remove
70. ay shows the system status and menu options The keys are grouped according to function 2500 psi FIGURE 4 1 MODEL 7250sys FRONT PANEL Numeric Keypad This includes the number keys the decimal point and the change sign key The UNITS key changes between units of measure MODE held down for 5 seconds changes the language It is also used to change between units of measure such as gauge and absolute MEASURE is used to place the system into measure mode CLEAR key will clear the numeric entry field The ENTER key accepts the entered number or contirms a command Function Keys These are the six keys that run vertically beside the display The label shown in the display beside each key identifies their function These functions will change based on which screen you are operating For ease of communication throughout the manual we refer to these keys as F1 through F6 We consider the top key to be F1 and the bottom Rotary knob The rotary knob select a field tor editing and are used for small pressure changes pressure jog at the main menu of the single display mode CANCEL PREVIOUS These keys are used to stop undo or exit the current operation The CANCEL key returns all edited fields on the current entry screen to their original values It also stops the current program sequence or calibration process The PREVIOUS key exits the curre
71. by a line feed hexadecimal OA Integer responses are returned as one or more digits Boolean values ON and OFF values are always returned as numbers with zero for OFF and one for ON Floating point values are returned the format d ddddddddE dd 29 9 REMOTE OPERATION 5 4 3 ANSI IEEE 488 2 1987 COMMAND SUMMARY GES Clear Status ESE Event Status Enable Query ESE number Event Status Enable ESR Event Status Register IDN Identification OPC Operation Complete Query Returns 1 OPC Operation Complete RST Reset SRE Service Request Enable Query SRE number Service Request Enable STB Status Byte Query TST Self Test Query WAI Wait No operation 5 4 4 SCPI COMMAND SUMMARY The current value associated with SCPI command may be read by appending question mark to the command For example CALC LIM UPP will return the current upper pressure limit MEASure PRESsure Main Pressure SLEW Main Slew Rate PRESsure2 Sensor A Case Reference PRESsure12 Sensor B Case Reference PRESsure22 Sensor C Case Reference PRESsure32 Sensor D Case Reference PRESsure42 Sensor E Case Reference PRESsure52 Sensor F Case Reference PRESsure3 Sensor RPT PRESsure4 Controller A PDCR PRESsure14 Controller B PDCR PRESsure24 Controller C PDCR PRESsure5 Sensor A 55 15 2 Sensor B PRESsure25 Sensor C PRESsure35 Sensor D PRESsure45 Sensor E PRESsure55 Sensor F
72. connected to the pressure generation point A digital controller on the board drives two solenoids in the pneumatics section to form a high speed closed loop controller 2 3 4 EEE 488 INTERFACE The DPC s IEEE 488 GPIB interface card which plugs directly into the Back plane Board provides the DPC with an IEEE 488 interface This interface allows the user to automate the measurement and control processes 2 3 5 FRONT PANEL The Front Panel contains the active matrix TFT color display rotary knob and rubberized keys used to operate the DPC 2 3 THEORY OF OPERATION 2 4 PNEUMATICS MODULE The DPC s Pneumatics Module varies depending on whether the DPC is a Gauge mode Absolute mode or a Simulated Absolute mode instrument Gauge mode DPC s reference their measurements to atmospheric pressure whereas Absolute mode DPC measurements are made with respect to sealed vacuum A Simulated Absolute mode DPC has a barometric sensor in addition to a gauge Bourdon tube sensor The DPC adds the barometric reading to the Bourdon tube reading to obtain a Simulated Absolute value It can operate as a Gauge mode instrument if the user selects to not add the reference pressure The valves filters and transducers that make up the pneumatics module of a Gauge mode or Simulated Absolute DPC are shown in Figures 2 2a The schematics for the Absolute mode DPC is shown in Figures 2 2b In the sections that follow the Zero Isolation Apply and Release valv
73. ctions for entering each step of a new program are included below 1 Ensure that the units limits and control parameters have been set to the desired values The program is entered trom the Program Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Program F4 Named Programs Delete MENU PROGRAM MENU Use the rotary knob to highlight new Press Edit F4 Since new was highlighted the DPC will create a new program and give a default name of NAMEnn where nn is a two digit number The program editing screen will appear displaying the first step Program 00 Cycles 1 Pressure Dwell Max Step psi psi sec sec 0 000 Delete MENU PROGRAM EDIT MENU 4 21 LOCAL OPERATION 5 Using the numeric keypad enter the values for Pressure Tolerance Dwell time and Max time pressing ENTER after each value The rotary knob may be used to skip fields 6 At the O step enter the next pressure and the DPC will automatically insert a new pressure step 7 Repeat steps 5 and 6 until the test sequence is complete The Tolerance Dwell time and Max time will default to the value programmed in the first program step and only need to be changed if a different value is desired for a particular step 8 lt is often suggested that the last point in a calibration program is to vent the pressure to atmosphere This can be achieved by selecting the VE
74. d 4 6 2 2 Zeroing Ruska recommends that the DPC be zeroed once a day to maintain optimal performance The zero drift specification is defined in Appendix A under General Specifications Refer to Section 6 4 5 for the zeroing procedure On gauge mode instruments the zeroing procedure automatically ties both test and reference ports of the Ruska quartz sensor together and performs the zeroing routine When operating a system that has the absolute mode with evacuated reference a vacuum pump and vacuum sensor is used to zero the instrument The vacuum sensor is installed in a port that is located internally to the DPC very near to the Ruska quartz sensor When initiating the zeroing command in the DPC it will cycle the internal valves allowing the external vacuum pump to pull a hard vacuum on the Ruska sensor It is recommended that the sensor be pulled down to a vacuum of less than 200 mTorr preferably less than 100 mTorr in order to obtain a proper zero The DPC can zeroed at higher vacuum levels however the uncertainty of vacuum sensors tend to increase at higher vacuum levels therefore the uncertainty in the DPC would also increase if zeroed at higher vacuum levels Once the vacuum level is stable the user enters the vacuum level as indicated by the vacuum gauge and then the zeroing procedure completes Please refer to the Maintenance Section Section 6 0 of the manual for more detailed information regarding the zeroing procedure of
75. d gt Zero all quartz sensors simultaneously en em gt View sensor coefficients ESTE RUNE Select sensor a gt Enter Program Menu Run program test sequence gt Delete saved program gt Change the configuration of a program Limit etc gt Edit program set point tolerance dwell etc gt Change program gt Enter test menu gt Sweep pressure between points cycles Perform self test gt Display IEEE 488 remote status gt Display RS 232 serial remote status gt Display solenoid status gt Tune control valve parameters gt Display sensor readings gt Display sensor temperature readings gt Display sensor vacuum readings gt Screen saver LOCAL OPERATION 4 2 FIGURE 4 2 MENU TREE 4 3 LOCAL OPERATION The F3 key places the unit in Vent mode This opens the test port to atmosphere and rapidly reduces the pressure ENTER is required to confirm the operation The F5 key places the unit either the stop or the jog mode and the rotary knob is then used to set the control set point by the correct step or jog amount To go to one of the menus press the F6 key 4 1 TUTORIAL To begin the tutorial first verify that the DPC is powered up and that the pneumatic connections have been
76. d Commands for Programmable Instruments Version 1991 0 Value Description and Corrective Action 103 Invalid Separator Check punctuation in the SCPI command 104 Data Type The type of parameter data is incorrect 109 Missing Parameter No valid parameter was found for the SCPI command 110 Command Header The command name is not valid 113 Command Unknown The command specified does not exist 114 Header Suffix The numeric suffix for the command is out of range 221 Settings Conflict The command could not executed due to the current state of the DPC Some commands cannot be executed while a program self test or calibration is in progress Out of Range The value is not within the valid range For pressures check high and low limits Cannot create program Program memory is full Illegal Program Name The name specified is not valid or does not exist Program Currently Running The command cannot be executed while a program Is running Program Syntax Error The syntax of the program definition is not correct 222 281 282 284 285 286 Program Runtime Error An error occurred while running the program Usually the setpoint is out of range 313 Calibration Data Lost The calibration data has been lost and the unit must be recalibrated 315 Contiguration Data Lost The configuration data has been lost Check all parameters to be sure they are correct High Limi
77. d the image file 6 Update7 should display Complete Note when updating the controller code the 7250sys will display various error messages This is expected The front display will freeze on the 7250sys when the controller code is being downloaded It will operate properly once the download 15 complete Finally the main software only reads the software versions on power up So follewing the controller code upgrade pressing the MENU TEST REMOTE SERIAL2 keys will only show the new revision level of the controller code after power is cycled on the 7250sys 6 9 REPLACEMENT PARTS The following is a list of the common replacement parts used in the Model 7250sys DPC Low Pressure Manifold High Pressure Manifold Valve Maximum Full Scale Maximum Full Scale Identification Pressure Range 1000 psi Pressure Range 1000 2500 6895 kPa psi 6 9 20 7 MPa ____________ VaveBody Valve Coil Valve Body Valve Coil 88 1076 88 1078 J MAINTENANCE 6 20 Part Number 7250sys 109 7250sysxi isolation manifold valve body 88 1055 7250sysxi isolation manifold valve coil 11 763 TFT Display 11 764 Display Inverter Electronic Board 7000 70 Sensor LED Lamp Assembly 7000 71 Sensor Photocell 72505 5 111 Photocell Adjustment Tool 62 293 Power Supply 23 906 Fan 7250sys 100 005 Rotary Encoder 7215 PCA KEY Front Panel Keyboard Electronic Card 6 10 PRESSURE INTENSIFIER OPTION Some s
78. dicates a cardinal point The operator can then read the higher resolution DPC to determine the actual pressure value when the mechanical gauge is indicating a cardinal point The Step Jog the F5 key toggles between Step and Jog to switch between these modes press the function key 5 F5 4 5 1 STEPPING Assure that the word Step is highlighted in the Step Jog the F5 key Using the rotary knob rotate the knob clock wise to increase the set point or counter clock wise to decrease the controller set point The scratchpad will be updated to a new set point The step size detaults to 10 of full scale Press ENTER to accept the new set point 4 5 1 1 Setting Step Size From the Main Menu press Menu F6 Setup F2 and then User F2 Using the rotary knob move the cursor to highlight Step Size Enter the desired step size in the current pressure units and press ENTER 4 5 2 JOGGING Assure that the word Jog is highlighted in the Step Jog the F5 key From the Main Menu the pressure set point can be modified by rotating the rotary knob clockwise to increase pressure and counterclockwise to decrease pressure Each increment or decrement will change the pressure in the least significant digit Continually rotating the rotary knob the pressure will continue to change until the rotation is stopped 4 6 MENU The menu key is used to access the less commonly accessed configuration type functions This accesses the Mode Setup Calibr
79. e coefficients generated during the calibration procedure as discussed below When the user performs a three point calibration the DPC s software creates the three coefficients based on user s zero mid point and full scale adjustments From then on the nonlinear term given above is subtracted from the total pressure current curve to achieve the desired linear pressure current relationship On 7250sys and 7250sysi multiple quartz sensor ranges are used order to provide the percent of reading specification In these instruments a total of three points per range with one point shared between two ranges is required Therefore for the 7250sys 5 point calibration is performed and for the 7250sysi 9 point calibration is performed to fully characterize the Ruska quartz sensors 2 6 4 AUXILIARY SENSORS Auxiliary sensors are sensors such as the oven temperature sensor These are reference sensors aligned at the factory and are utilized by the firmware 2 6 4 1 Case Reference Vacuum Sensor Option A case reference vacuum sensor is a user selectable option This option includes a vacuum sensor installed into the test port on absolute units and the sensor case reference port on differential units and can be read directly by the DPC On units that have been purchased with the Absolute Mode with Evacuated Reference this sensor is used to zero the DPC and it is used to continuously monitor the DPC Case reference while operat
80. e operating a warm environment or when multiple systems are housed in consoles without adequate ventilation the system may become too hot and generate the oven control failure error message lf operating the instrument in a warm environment and the oven duty cycle is at a low percentage gt 10 you will need to turn the fan on See Section 6 7 for fan operation When the operator changes the status of the fan it will remain in that condition until the operator changes the setting THEORY OF OPERATION 2 12 MENU DISPLY TEMP MENU 2 7 1 5 Pressure Reading and Correction The sensor s analog output is processed by an analog to digital circuit that results in an output referred to as counts This output is corrected for the applied effects listed below The counts are linearized and the resulting pressure value is corrected for the variations in head pressure vacuum case effect and oven temperature effects The following equations are used by the control algorithm to adjust and correct the pressure signal Zero Coefficients CsH Zero correction for High FSR Full Scale Resistors Value is in counts 7 381 975 full scale of current sensor CsL Zero correction for Low FSR Value is in counts 7 381 975 full scale of low FSR HsZ Hardware zero correction 0 to 4095 center is 2048 SsZ Zero corrections scaling factor Ratio of High FSR to Low FSR Used only when Case Effect Coefficient or Oven Temperature Coefficient
81. ential or Absolute The Main Menu can always be reached by repeatedly pressing PREVIOUS The model 7250sys is designed such that all of the commonly used functions are accessible by a direct key on the key pad or from a top level function key Less commonly used set up type functions are accessible through the menu function key MAIN MENU 4 7 LOCAL OPERATION NOTE For DPC s with pressure ranges greater than 100 psi 700 kPa the supply pressure port must be plugged or connected to a properly set pressure supply in order to measure pressure greater than 100 psi 700 kPa 4 3 CONTROLLING PRESSURE The Control F2 function key is used to place the DPC into the Control Mode A pressure set point should be entered into the DPC prior to placing the unit into the control mode This 15 to assure that the operator is aware of the set point valve prior to entering into the control mode 4 31 SETTING THE PRESSURE SET POINT The pressure set point is the destination of the pressure control algorithm It should be set before entering Control mode The pressure set point is set to zero at power up or whenever a pressure error occurs 1 The pressure set point can be set trom the Main Menu 2 Use the numeric keypad to enter the new pressure set point in the current pressure units 3 Press ENTER to accept the entry or press CLEAR to clear the numeric scratchpad NOTE The set point can also be changed using either the Step or the
82. er 3 months Uncertainty Analysis One Year Calibration Interval Uncertainty Ruska Model 7250sys 2 sigma A Performance Linearity Hysteresis Repeatability 0 003 of Each Range and Temperature Control in Passive Control Mode 2 sigma Expanded Uncertainty RSS 0 003 of Full Scale RSS with 0 0076 of Reading per year A 3 APPENDIX A 1 7 ABSOLUTE MODE With the 7250sys there are 2 methods of operating the system in the absolute mode These are by adding a Barometric Reference Sensor to the system to monitor the barometric pressure and add this value to the gauge reference quartz sensor Or the second is to evacuate the reference port of the Ruska quartz sensor and then monitor the residual vacuum in the reference port and correcting for this residual vacuum In either case the expanded uncertainty of the system must account for the potential uncertainty of whichever sensor is used in the system to allow it to operate in the absolute mode Therefore the uncertainty of one of these sensors would be combined RSS Root Sum Squared with the expanded uncertainty of the system A 1 7 1 Barometric Reference Sensor Option The two sigma expanded uncertainty of the barometric reference sensor is estimated to be less than or equal to 0 002 psi 13 8 Pa per year This uncertainty component should be combined RSS with the primary sensor uncertainty when operating in the absolute mode with a barometric refere
83. erefore reducing the calibration interval would not improve the expanded uncertainty of the device 1 3 SHORT TERM STABILITY relates to the zero drift characteristics of the instrument This generally is classified as short term drift since the instrument can re zeroed without performing a full calibration as required to correct for long term span drifts The magnitude of zero drift can be assessed based on the length of time between re zeroing the instrument A 1 4 UNCERTAINTY OF THE STANDARD used to calibrate the transfer standard This is the expanded uncertainty of the calibration standard that was used by the manvfacturer to calibrate the digital transfer standard This should be the expanded uncertainty of the calibration standard and include all sources of uncertainty that would influence the calibration standard including the uncertainty from the National Standards Laboratory that the standard is traceable It should also be noted that when the instrument is re calibrated the uncertainty of the device is influenced by the uncertainty of the calibration standard that will be used to perform the re calibration Therefore the uncertainty analysis should be evaluated following each re calibration If the instrument is re calibrated using a different calibration service provider than the manufacturer the uncertainty of the standard that the calibration service provider used to perform the calibration would need to be substituted for the
84. eroing screen will appear NOTE The next step requires the use of a properly calibrated standard This zeroing process does contribute directly to the overall accuracy of the system since the pressure applied to the sensor is a non zero differential pressure 5 Enter the current barometric pressure Press ENTER 6 4 6 4 ZERO ALL All of the primary dual range sensor can be zeroed in the system at one time Verify that the Reference Port is open to atmosphere Enter the Calibration screen by selecting MENU CALIBRATION Select Zero All F3 Do NOT press the Calibrate button Do not disturb the instrument while zeroing is in process Watt for the zeroing procedure to finish Press PREVIOUS to return to the Main Menu O 6 5 SENSOR PHOTOCELL ZEROING If the error message Mechanical Zeroing Needed is displayed the sensor photocell must be zeroed The following steps describe this process Press the MODE key to select the desired channel 6 13 MAINTENANCE CAUTION The DPC should only be opened by qualified electrical mechanical service technicians Lethal voltages are present and exposed in the power supply and display 1 Identify which dual range sensor requires mechanical zeroing 2 Remove the DPC s top cover 3 Locate and remove the plastic zeroing plug located in the side of the sensor oven assembly 4 Enter the Zeroing screen by selecting MENU CALIBRATE 5 Select the
85. es are all 24 volt DC solenoid valves that are either open or closed depending on the DPC s operational mode Their behavior is summarized in Table 2 2 REFERENCE SUPPLY EXHAUST PORT PRESSURE PORT PORT RELEASE BAROMETRIC REFERENCE SENSOR SIMULATED ABSOLUTE OPTION INNER LOOP CONTROL SENSOR pun E EN DUAL RANGE e X DUAL RANGE ISOLATION PRIMARY SENSOR B Pa I 3i VACUUM Y SENSOR 5 7 Option None SENSOR Option FIGURE 2 2 MODEL 7250sys DPC GAUGE PNEUMATICS DIAGRAM 0 36 to 2500 psig 2 5 kPa to 17 2 MPa Full Scale Ranges Note this diagram depicts the components shown in the Primary Module A of Figure 2 1 THEORY OF OPERATION 2 4 Control Mode Zeroing TABLE 2 2 MANIFOLD SOLENOID VALVES STATES 2 4 1 MEASURE MODE PNEUMATICS Figures 2 2 summarizes the Pneumatics of the DPC 2 4 1 1 Reference Port For gauge measurements the Reference Port is normally left open to atmosphere This port can be tied to the reference port of the device under test to assure a common reference The Reference Port is isolated from the Test Port by a solenoid valve that is closed during the DPC s Measure and Control modes When the user commands the DPC to perform the zeroing process the solenoid automatically opens and the pressures on the Reference Port and Test Port become equal The Reference Port is protected by a relief valve 2 4 1 1 1 Barometric Sensor
86. es including disturbances in the atmospheric pressure The reference side must be very caretully controlled or changes due to wind air handlers doors shutting etc will cause major variations The DPC tracks these changes but it may not track in the same way as the device under test To control these changes it is recommended that the reference port of all relevant devices be tied to the reference port of the DPC The reference port can be sealed from atmosphere in most applications where the test times are relatively short This isolates the port from pressure changes in the atmosphere and results in very stable pressure measurement and control 3 3 INSTALLATION It the test times are relatively long in addition to connecting the reference ports together they should also be connected to a tank with a volume of 200 cubic inches or better The tank should be vented to atmosphere through a small orifice bleeder valve at the other end of the tank The entire reference assembly should be shielded rapid fluctuations in air temperature and flow The vent valve should be set experimentally an environment with no temperature change it would be closed In an environment with no pressure fluctuations it would be wide open The heat from the DPC oven and control valves will cause some temperature variations Thus the appropriate setting varies but a good compromise can be found To observe the variations connect the reference as discussed and
87. fect on the zeroing procedure 6 4 6 1 Gauge and Vacuum Negative Gauge Instruments 1 Verity that the Reference Port is open to atmosphere 2 Enter the Calibration screen by selecting MENU CALIBRATION 3 Select Zero F1 Do NOT press the Calibrate button 6 11 MAINTENANCE Pressure 0 Out of Range Temperature 0 00 Stable Reference 0 000 Stable 4 Do not disturb the instrument while zeroing 15 in process 5 Wait for the zeroing procedure to finish 6 Press PREVIOUS to return to the Main Menu 6 4 6 2 Absolute Mode with Evacuated Reference A vacuum pump must be connected to the reference port A vacuum gauge should be installed for measuring the case reference pressure This gauge should be installed internal to the Ruska quartz sensor oven assembly 1 Select the desired pressure units using the UNITS key You can change both the unit of measure that the DPC is displaying Pressure and the unit of measure for the vacuum sensor It is not required to have the DPC displaying pressure in the same unit of measure as the vacuum sensor To change the unit of measure for the Vacuum sensor press the UNIT key and then the Vacuum F2 key 2 Enter the Calibration screen by selecting MENU CALIBRATE Select which sensor range 15 to be zeroed 4 Select Zero F1 Do NOT press the Calibrate button When initiating the zeroing command in the DPC it will cycle the internal valves allowing the external vacuum
88. ference port only absolute only instruments do not need a moisture filter 6 3 4 PARTICLE FILTERS Refer to Appendix A for air supply quality requirements During normal operation the DPC transfers gas both into and out of the device under test DUT When necessary the user is expected to use and maintain an in line disposable particle filter to protect the DPC s pneumatics from any contamination that may exist in the DUT 6 3 5 VACUUM PUMPS Periodic checks of the user s vacuum pumps for oil levels It is very highly recommended that a power down vacuum venting valve is installed onto the vacuum pumps to ensure minimal chances of oil contamination from the vacuum sources These are normally open solenoid valves that are powered through the vacuum pump power switch When MAINTENANCE 6 2 the vacuum pump is turned on the solenoid valve is energized and closes allowing the pump to operate normally When the pump is turned off power is removed from the solenoid and the vacuum is vented to atmosphere Periodic changing of vacuum pump oil as recommended by the vacuum pump manufacturer should also be done 6 3 6 PROCESSOR BATTERY The processor board uses a lithium battery to maintain time and date information This battery has a varying life If the instrument is left on 24 hours a day it may last 5 to 10 years It the instrument is stored it may only last one year Annual replacement is recommended To replace the battery 1 Turn off p
89. ge of the system Friendly Display The DPC s color active matrix TFT display combines a bright low glare readout with a wide viewing angle During normal operation the measured pressure is easily visible from a distance of 10 feet 3 meters Adjustable Pressure Display The pressure display may be adjusted to show one decimal greater than or less than the default resolution Ease of Operation An intuitive menu driven interface makes the DPC easy to use Frequently used selections such as the units of measure are restored to memory each time the DPC powers up Easily Programmable The DPC s powerful microprocessor provides the basis for smart electronics With a few simple keystrokes the user can set limits on the system pressure create unique units of measure program a test sequence and more Modular Design The sensing element pneumatics electronics and user interface are separated into modules making maintenance faster and easier Power On Self Test Upon power up the DPC quickly tests its hardware and software After the DPC completes this test the user can select more extensive self tests for the pneumatics and electronics Ease of Calibration Calibration may be performed either remotely or entirely from the front panel No disassembly is required and there are no potentiometers to tune On single sensor units only a three point calibration is required to fully characterize the instrument On instruments that integ
90. good their warranties ii INTRODUCTION COPYRIGHT NOTICE Copyright 1997 by Ruska Instrument Corporation All rights reserved This document may not be reproduced in part or in whole without the express written consent of Ruska Instrument Corporation DISCLAIMER No representations or warranties are made with respect to the contents of this user s manual Further Ruska Instrument Corporation reserves the right to revise this manual and to make changes from time to time in the content hereof without obligation to notity any person of such revision TRADEMARK NOTICE Meme 9 RUSKA is a registered trademark of Ruska Instrument Corporation Trademarks or tradenames are subject to state and federal laws concerning their unauthorized use or other infringements The fact that the product marks or names in this manual do not bear a trademark symbol DOES NOT mean that the product name or mark is not registered as a trademark or tradename Any queries concerning the ownership or existence of any trademarks or tradenames mentioned in this manual should be independently contirmed with the manufacturer or distributor of the product lii INTRODUCTION REVISION NOTICE RELEASE REV DATE OF DESCRIPTION NUMBER RELEASE 7250sys 1D01 02 06 04 Original release See DC RO 24161 1V INTRODUCTION REVISION HISTORY RELEASE 7250sys 1D01 Revision A 02 06 04 Original release See DC RO 24161 INTRODUCTION 0 000 Dif psi
91. he off position Disconnect the power cable from the DPC power receptacle Disconnect all pneumatic lines from the DPC s back panel O A WN Plug all ports 7 2 PACKING INSTRUCTIONS To prevent shipping and handling damage to the instrument adhere to and strictly follow the instructions below If shipping a cart system within USA it is recommended to ship either via air freight electronic van ride If the primary measurement and control components are removed from the system and returned to Ruska the governing discipline in ensuring damage free shipment is to ensure that the possibility of handling shocks to the DPC is minimized and or prevented during transit Ruska accomplishes this task by cradling the DPC within two foam cradles that are encapsulated within a double walled corrugated box The DPC is restrained and supported but still has resilience The materials used in the packaging operation are foams that have a minimum impact rating of not less than N 95 If polyfoam or rubber foam other than that used in the original packaging 15 to be used cut it into strips so that it will not present a large rigid surface to the DPC Ruska has found that corrugated cardboard boxes provide the best packaging exterior The box must have an impact rating of 275 and be of double walled construction This type of box will sustain most types of damages incurred during the shipping and handling process but ensures that the c
92. in Menu appears press Menu F6 then Program F4 2 Use the rotary knob to highlight the name of the program 3 Press Run F1 The program run screen will appear Stop will be highlighted showing that the program is not currently running quu gnum penam pesas penu pee peste nuuc pesci ponam a E MENU PROGRAM RUN MENU 4 Press Run F2 The contiguration of the DPC stored with the program is restored the pressure set point is set to the pressure value in the first step and the DPC is placed in Control mode Run will now be highlighted and the program will proceed through its steps 5 To pause the program press Pause F3 Pause will now be highlighted and the DPC will continue controlling to the current set point The DPC will maintain control of the current set point until further instructions from the operator Press Continue F4 to resume the program 6 To stop the program press Stop F5 The program will stop running but the DPC will continue controlling to the current set point 4 6 4 MENU TEST The Menu Test section of the system is used to perform a number of the diagnostic and tuning functions that are available with the 7250sys LOCAL OPERATION 4 26 4 6 4 1 Menu Setpoint 0 00 Remote Control MENU TEST MENU Test Sweep Test The sweep function can be used to automatically exercise the elastic sensing element of the device under tes
93. ing in the absolute mode 2 7 SOFTWARE The DPC is a digital software based instrument The controlling software uses a PID algorithm and allows for user definable units and onboard programming The software control loop is a digital outer loop with a high speed inner loop 2 7 1 SOFTWARE SAFETY CONTROLS 2 7 1 1 Preventing Operator Errors The operator is required to verify a change to Control mode or Vent mode by pressing the Enter key Additionally the control set point is set to zero on power up or when any of the limit errors occur 2 7 1 2 Pneumatic Errors The DPC continually monitors the pressure for low high and slew rate of change limits When these limits are exceeded the DPC is returned to Measure mode shuts off the apply and exhaust control valves and an error message is generated Additionally a vent limit may be set The DPC will go to Vent mode when the pressure exceeds this limit 2 7 1 3 Shut Offs 2 11 THEORY OF OPERATION Measure mode can be entered at any time by pressing the Measure key on the main keypad with no further acknowledgment required The DPC will turn off the controller 2 7 1 4 Oven Control The oven temperature is controlled via a pulse width modulated signal The time the heater is on can be varied from 0 to 100 The pulse width at startup is initialized to the previous value which was stored in battery backed CMOS RAM The oven control is a PID controller updated approximately every 7 seco
94. iode assembly is mechanically adjusted so that the light spot is centered between each photocell In this zero position the outputs of the two photodiodes provide energy used to maintain the quartz assembly in its zero position thus a force balance is created As pressure is applied in the helical tube the entire apparatus attempts to rotate This causes the mirror to move the reflected light spot to shine more on one photodiode than the other The Sensor Board see Section 2 6 2 then responds by changing the current to the electromagnetic coils that through interaction with the permanent magnets the helical tube to return to its zero position The amount of current required to do this is proportional to the pressure applied across the helical tube Thus the pressure is determined by the amount of current required to return the helical tube to its zero position On Absolute Models the process is similar except that the Bourdon tube is permanently evacuated to less than 0 1 mtorr and sealed at the factory and the test pressure is applied to the sensor case With this configuration all test pressures are measured with respect to vacuum 2 9 THEORY OF OPERATION FLEXURE FIGURE 2 5 SHAFT MAGNET SECTION LEFTHAND RIGHTHAN SHIFTING SPOT SHOWN AT 2 ase x uA TUNE LT 7 QE KS f Ne N EDA O ACE Y NU OSITION
95. irection by this same width Again tighten the Allen screw Now the width of the yellow line should be minimized Tap on the bracket with a screwdriver handle to relieve mechanical stress Continue to tap on the bracket until the counts stop changing the zero moved significantly as result tapping the bracket repeat this procedure as necessary Reinstall plastic zeroing plug 6 15 MAINTENANCE 16 After the unit has become thermally stabilized perform a normal instrument zeroing procedure Refer to Section 6 4 5 X E i d NSEI WELL CENTE FIGURE 6 5 PHOTOCELL LOCATION 6 6 OPTIMIZING CONTROL The performance of the controller may be optimized for certain environments or performance criteria by adjusting the values available in the Control screen The Control screen is available from the Main Menu by pressing Menu F6 Test F5 Control F6 The 7250sys has multiple control channels integrated into the system It is important to identify the range of the channel that requires auto tuning and it would be recommended to only tune the channel that requires tuning When in the Auto tune screen pressing the MODE key on the front panel toggles between the various controllers in the system The ranges are identified by the full scale pressure range of the controller The Control screen is shown below AutoTune AutoTune Full Calibrate MENU TES
96. l mode The Control On and Off Band provides a tolerance around the pressure set point in the current unit of measurement The Controller will control the pressure to the commanded set point Once the actual pressure is within the user detined Control Off Band tolerance the controller will shut off The pressure will remain at this level only changing by the thermal influences or leaks in the system The controller will remain off until it reaches the Control On Band limit The controller will then re activate and control the pressure back to the Control Off Band tolerance This mode of operation removes any added uncertainty in the measurement system due to the controller since the controller is Passive during the high accuracy pressure measurements As an example if a 100 psi 690 kPa full scale DPC was set up with the Control Band at 0 001 psi 0 007 kPa and the Control On Band set to 0 005 psi 0 035 kPa This would place the DPC in a Passive control mode If the DPC was placed into the control mode with a pressure set point of 10 psi 69 kPa it would control up to the 10 psi 69 kPa value Once it reached a pressure of 9 999 psi 68 993 kPa the active control would turn off Due to the thermal effects caused by pressurizing the system the pressure will start reducing in the system Once the pressure reaches 9 995 psi 68 965 kPa the active controller would automatically turn on and control the pressure back to 9 999 psi 68
97. le to quantity the magnitude of the potential error source and combine these into an overall uncertainty statement To determine the expanded uncertainty on any manufacturers pressure Transfer Standard TS you must identity the following four primary influences 1 Performance specifications of the TS 2 Long term Stability of TS 3 Uncertainty of the standard used to calibrate the TS 4 Environmental or installation influences that could cause errors in the TS 1 1 PERFORMANCE SPECIFICATIONS are the short term measurement properties of the device These traditionally include linearity hysteresis and repeatability properties of the transfer standard There often is considerable contusion with the performance specification because different manufacturers use different terms to describe the performance characteristics of their instruments The two most common terms used are Accuracy and Precision In both cases as a minimum the manufacturers define these terms to be the combined effects of linearity hysteresis and repeatability Since the manufacturer defined the terms they used this should not be a problem However it is common that the users definition of these terms differ from the manufacturers and therefore cause considerable confusion For instance the user may believe that the term Accuracy includes all sources of uncertainty This would include items 1 through 4 listed above which would be an all encompassing s
98. leaks in a system following a pressure step the pressure in the system changes due to temperature effects When operating an Active control system the controller continuously monitors any pressure variances in the system and compensates for these effects to hold the pressure at the set point The benefit of the Active control is that it can maintain the pressure at the commanded set point even when there are slight leaks in the system or the system is not thermally stable 4 11 LOCAL OPERATION The second approach is to control the pressure in the system to a set point and then to shut off the Active controller We describe this as a Passive control mode Following a pressure step and the controller becomes passive the pressure will continue to change in the system due to thermal effects However these thermal effects will stabilize over time Once the system has thermally stabilized pressure measurements can be made in the system without any pressure noise injected into the system as a result of having an Active controller in the system The result would be that the controller would not add any additional uncertainty to the pressure measurement since it would be inactive during the measurement process For this method pressure will not be at a cardinal set point When the Control Off Band and Control On Band are set to zero the DPC operates in the Active control mode Setting a Control On and Off Band places the DPC in the Passive contro
99. less another person capable of rendering aid and resuscitation 15 present RESUSCITATION Personnel working with or near dangerous voltages shall be familiar with modern methods of resuscitation Such information may be obtained trom your local American Medical Association ELECTRO STATIC DISCHARGE SENSITIVE PARTS CAUTION Electrostatic discharge sensitive ESDS is applied to low power solid state parts which could be damaged or destroyed when exposed to discharges of static electricity Maintenance personnel are often not aware that an ESDS part has been damaged or destroyed because electrostatic discharges at levels less than 4 000 volts cannot be seen felt or heard COMPRESSED GAS Use of compressed gas can create an environment of propelled foreign matter Pressure system safety precautions apply to all ranges of pressure Care must be taken during testing to ensure that all pneumatic connections are properly and tightly made prior to applying pressure Personnel must wear eye protection to prevent injury PERSONAL PROTECTIVE EQUIPMENT Wear eye protection approved for the materials and tools being used INERT GASES Operation of pressure equipment may be accompanied by the discharge of inert gases to the atmosphere The result is a reduction of oxygen concentration Therefore it is strongly suggested that exhaust gases not be trapped in the work area Vii INTRODUCTION TABLE OF CONTENTS WARRANTY yee
100. m sets pressure display resolution returns to default resolution ABSolute DIFFerential GAUGE TARE RANGE UPPer UPPer number LOWer LIST CONTrol REFerence HEIGht lt number gt MEDium N2 AIR SOURCE PRESsure LEVel IMMediate AMPLitude lt number gt MODE FIXed LIST TOLerance number SLEW number 5 7 full scale value in units calibrated set 7610 triple range returns low cal point list installed sensor ranges list installed controller ranges gas head height gas head medium pressure control setpoint set control mode specifies output tolerance set slew rate REMOTE OPERATION number number OFF number OVERshoot ON OFF 1 0 LIST PRESsure number number POINtS DWELI number number POINtS TOLerance number number POINtS DIRection UP DOWN COUNt number STATus OPERation EVENT CONDition ENABle number QUEStionable EVENT CONDition ENABIe PRESet SYSTem BEEPer freq length DATE lt year gt lt month gt lt day gt ERRor KLOCK ON OFF 1 0 TIME lt hour gt lt minute gt lt sec gt VERSion LANGuage COMP 6000 SCPI 510 PRESet COMMunicate SERial RECeive TRANsmit BAUD number PARITY EVEN ODD NONE BITS 7 8 SBITs 12 GPIB ADDRess number TEST REMOTE OP
101. mple using the information from table 2 1 the conversion factor for millitorr or one micron of mercury at 0 C is calculated as follows 1000mTorr Torr Imm Hg 0 0 1450377psi mlorr kPa X Torr 1 0 0 0193377psi 1 kPa thus the conversion factor simplifies to mTorr kPa x 7500 6180 Setpoint 0 00 kPa 7500 61800 0 0 0098692 10 MENU SETUP UNITS MENU 4 15 LOCAL OPERATION 1 The pressure units are defined from the Units Define Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 then Units F3 2 Use the rotary knob to highlight the desired user defined unit and then select the Edit Name F1 function key 3 The following sequence is used to change the name of the selected unit MENU SETUP UNITS EDIT NAME MENU a Use the lt F4 or gt F5 key to highlight the desired character in the matrix b Use the rotary knob to change the character Repeat steps a and b until the desired name 15 entered Press the Clear key to start over d Press the Done F6 key when the name change is completed 4 Use the rotary knob to highlight the desired user defined unit that has just been renamed 5 Use the numeric keypad to enter the conversion factor and press ENTER to accept 6 Press PREVIOUS three times to return to the Main Menu The new unit definition may now be selected using the units key 4 6 1 4 Menu
102. n its entirety Verity that the DPC is in Measure mode Section 4 0 Enter the Calibration screen by selecting MENU CALIBRATE When you first enter the Calibration menu the top line of the display will indicate which sensor is being the viewed The sensors coefficients are then shown below the sensor label The first sensor that is shown is the primary measuring sensor This is indicated by the word Primary displayed in the top of the display To cycle through the various sensors that exist in the system you would press the Sensor F6 function key The two common sensors that would be calibrated would be the Ruska sensor which would be labeled as Primary and if the unit has the optional Barometric Reference sensor this would be labeled as Atmospheric Sensor To edit the calibration coefficients press the EDIT button If the calibration access code is enabled enter it at the prompt The first calibration screen will appear NOTE To exit the calibration procedure before the calibration coefficients have been 6 changed press CANCEL any time during the procedure Canceling restores all previous calibration values Use the rotary knob to highlight the coefficient to be edited The terms are coefficients of a linear regression analysis Use the numeric keypad and the ENTER key to enter a new value To correct a mistake in the edit field use the CLEAR key Repeat steps 4 and 5 until all coefficients
103. nance procedures 6 2 OBSERVING THE SOFTWARE VERSION NUMBER Follow the steps below to observe the DPC s software version number 1 If necessary press PREVIOUS several times to return the display to the Main Menu 2 Select MENU SETUP SYSTEM The software version number will appear on the screen 3 Press PREVIOUS to return to the previous screen 6 3 PREVENTIVE MAINTENANCE Although the DPC is designed to be nearly maintenance free occasional preventive maintenance is required to keep the DPC s performance optimal 6 3 1 INITIATING THE DPC S SELF TEST To test the DPC s hardware and software follow the steps below 1 If necessary press PREVIOUS several times to return the display to the Main Menu then press the MODE key to select the channel main menu 2 Select MENU TEST SELF faaciira Electrical Pneumatic MENU TEST SELF MENU 3 Press ELECTRICAL F1 The electronics self test will run and display the results The electronics test runs eight sets of tests on various parts of the electronic modules Table 6 1 describes these tests and the possible actions needed if a test fails The pneumatics test runs nine tests on the pneumatics module Table 6 2 describes these tests and the possible actions needed if a test fails 6 1 MAINTENANCE TABLE 6 1 ELECTRONICS SELF TEST Action on failure Part Tests the processor chip Replace processor board 7215 586 3 Tests
104. nce sensor A 1 7 2 Evacuated Reference Option The two sigma expanded uncertainty of the vacuum sensor used to monitor the reference pressure 15 estimated to be less than or equal to 10 mtorr 1 33 Pa per year This uncertainty component should be combined RSS with the primary sensor uncertainty when operating in the absolute mode with a evacuated reference vacuum sensor A 1 8 CONTROLLER SPECIFICATION When the system is in control mode the control noise is defined as how close the controller can maintain the control pressure to the commanded set point n the active control mode the 7250sys has a control noise specification of 0 00196 of each controller range On an 8 range system there are two control ranges One has a full scale range equal to the full scale of sensor Range A The other has a full scale range equal to the full scale range of the sensor range C On a 12 range system there are three controller ranges equal to the full scale of ranges A C and E In the Passive control mode since the controller shuts off when it reaches a user defined band about the commanded set point the uncertainty of the pressure measurement in not influenced by the controller A 1 9 TWO SIGMA EXPANDED UNCERTAINTY OF THE 7250sys Since the 7250sys automatically switches between multiple sensors selecting the highest performance sensor to monitor the pressure there are two ways to express the uncertainty of the system One method results in the
105. nd is received When only one unit is attached the Control C hexadecimal 03 command will clear the transmit and receive buffers and disable addressing When addressing is disabled the unit will respond to commands without being addressed 5 6 SAMPLE PROGRAMS 5 6 1 SAMPLE PROGRAM 1 7252 IEEE 488 CONTROLS PRESSURE 20 000 FS 2 Ec Sample Program 1 7252 GPIB IEEE 488 Controls pressure to 20 000 5 5 Ey a ae E NM E include lt stdio h gt include lt stdlib h gt include lt string h gt include lt conio h gt 5 11 REMOTE OPERATION include decl h a iM E DE Pa M Lc E IC x int device GPIB Device descriptor ehar buffer 256 purter for Anputy cubput str ngs 77 double pressure Pressure read from unit Tnt status Status register from unit int check errors v id 7000 char 67 void request 7000 char s Ecken IE P ONE E void main void ps c PHP NR x Initialize GPIB Interface device ibdev 0 First GPIB Board a GPIB Address of 7010 NO SAD No secondary addressing TILS 1 Second Timeout Gi No automatic EOI for transmit REOS LF Terminate read on Line
106. nds The sensor readings are accessed by pressing MENU DISPLAY TEMP The high accuracy quartz sensor is housed in a temperature controlled oven There is a 3 hour warm up time required prior to the DPC operating at its optimum precision The user can verify when the instrument is thermally stable by viewing the MENU DISPLAY TEMP screen and verifying that the temperature is at 50 C for each dual range sensor In addition to the temperature this screen will show the duty cycle of the oven When operating the system in either a very cold or hot environment if the oven in unable to maintain the temperature of the internal oven the DPC will generate an Oven Control Failure error messages The operator can review the temperature and duty cycle of the oven by pressing the MENU DISPLAY TEMP keys The unit must be have been warmed up for a minimum of 3 hours prior to determining the condition of the oven temperature control The temperature of the sensor should be controlled to 50 C The Duty Cycle indicates the amount of time in units of percentage that the oven control is turned on in order to maintain the oven at the proper set point of 50 C A unit that is operating properly after it has fully warmed up should indicate a sensor temperature of 50 C and a duty cycle between 10 to 9096 IF operating the instrument in a very cold environment and the oven duty cycle is at a high percentage 29096 you will need to turn the fan off If you ar
107. nemonics enclosed in square brackets are optional and may be omitted Some mnemonics are followed by an optional numeric suffix omitted the suffix defaults to 1 Multiple commands may be placed in a single message separated by semicolons Each command starts at the same level of tree where the last command stopped unless the command starts with a colon The first command in a message and any commands starting with a colon start at the root of the command tree IEEE 488 2 commands may occur between SCPI commands without affecting the tree level Command parameters are separated from the command name by one or more spaces Multiple parameters are separated by commas SCPI accepts numeric parameters with optional sign decimal point and exponent OFF is equivalent to zero and ON is equivalent to one Floating point numbers are rounded to the nearest integer commands accepting integer values only A message is terminated by a line feed hexadecimal OA Carriage returns tabs and other control characters are ignored 5 4 2 SCPI RESPONSE FORMAT Most values be queried by appending a question mark 2 to a command and specitying any parameters Commands ending with a question mark 2 in the command summary cannot be set only queried Multiple values trom a single command are separated by commas Responses from different commands in the same message are separated by semicolons The response message is terminated
108. nes all of the uncertainty components in quadrature RSS In this approach it is important to define the level of confidence that all of the uncertainty components are defined For instance all of the uncertainty specifications that GE Ruska APPENDIX A A 2 publishes are at the 2 sigma level which would be at a 95 confidence level Some manufacturers may state their uncertainty at different confidence level and therefore you would need to be able to convert from one to the other in order to compare the two devices For instance if a manufacturer states that they have an uncertainty of 0 005 FS and that the uncertainty is expressed at the 1 sigma level then it would be doubled to express it at the 2 sigma level i e it would be an 0 01 FS device at a 2 sigma or 95 contidence level The following two tables are uncertainty analysis examples for 7250sys based on a three month and a yearly calibration Uncertainty Analysis 3 Month Calibration Interval Uncertainty Ruska Model 7250sys 2 sigma A Performance Linearity Hysteresis Repeatability 0 003 of Each Range and Temperature B Stability 3 months 0 0019 of Reading per 90 days C Calibration Standard Ruska 2470 or 2465 DWG 0 0011 of Reading Temperature Included in A above 0 000 of Reading Control in Passive Control Mode 0 000 of Controller Range 2 sigma Expanded Uncertainty RSS 0 003 of Range RSS with 0 0022 of Reading p
109. no less than 3 inches of 95 foam strips Arrange the strips in the configuration illustrated in figure 7 1 Before sealing the carton include the following a Statement of the problem or service needed Be specific Include the name and telephone number of a knowledgeable technician for consultation b The part number serial number return address and purchase order number Seal the carton using gummed tape Address the carton to RUSKA INSTRUMENT CORPORATION 10311 WESTPARK DRIVE HOUSTON TX 77042 USA Label the carton with the following labels THIS SIDE UP HANDLE WITH CARE DO NOT DROP and FRAGILE If the original Ruska shipping carton is utilized for this shipment the above markings are preprinted on the carton SHIPPING INSTRUCTIONS Ruska recommends using air freight for transportation Surface transportation subjects the shipment to more frequent handling and much more intense shock In most cases if surface transportation is the mode of transport employed handling damage is likely Again it is essential that the procedures mentioned in sections 7 1 through 7 3 be strictly adhered to in order to prevent any shipping and handling damage to the instrument SIORAGE amp SHIPMENT 7 2 APPENDIX A SUMMARY OF SPECIFICATIONS A 1 UNCERTAINTY ANALYSIS To perform an Uncertainty Analysis on a measurement device you must be able to identify all of the parameters that influence the measurement You must be ab
110. nt menu and returns to the previous menu Figure 4 2 is a menu tree showing the relationship between all the menus in the system Refer to it for selections available under the menu To move to a lower menu press the function key with the correct label To move towards the main menu press the PREVIOUS key In the Single channel Main Menu screen the F2 key places the unit in Control mode ENTER must be pressed to actually enter the Control mode 4 1 LOCAL OPERATION gt Places the system in Control Mode Vents system pressure to atmosphere Step Jog gt Toggle between step and jog mode Menu Enter Sub Menus Setup 2 2 2 gt Enter Set up menu Limits gt Set pressure limits control band access code gt Set step size head corr filter amp display digits menee gt Set User Defined units of measure gt Set baud parity data amp stop bits GPIB address rnm gt Set date time reset amp view software version gt Enter calibration menu Zero Zero sensor gt Perform or edit calibration gt Zero sensor from calibration Calibrate sensors Password to edit calibration coefficients gt Select sensor to be calibrate
111. nt retval c Check for 77252 5 retval 0 while kbhit 4000 serial return TRUE status7 atoi buffer if status7 amp 4 0 break retval 1 request 40900 serial TOOT ERR iE 57 printf buffer return retval ene Int C 3 char ch if inportb portbase 2 amp 0x07 0x04 ch inportb portbase if ch XON transmit enabled TRUE else if ch XOFF transmit enabled FALSE else nig moe Lf ane in OURUN SIAE DIXI i 57 OBUCDOILD 0x20 0320 Check error bit Get error message REMOTE OPERATION serial initialize initialize serial port Ey VOL Seria Inverts J char msg 10 wE unsigned v portbase 0x3F8 COML COM2 OXxA2ES8 intnum gt As COMI 994 COM2 3 xy Outportb 03 7056 outportb portbase 1 0 outportb portbase 0x0C 9600 Baud outportb portbase 3 3 7 8 Databrits Parity 1 Stopbrt Vector getuect 3e 9 5 Save old interrupt vector 1 8 serial int Set new interrupt vector 0x21 Enable interrupt V amp
112. ogram will depend on the current setup of the DPC the current configuration is stored with the program the user should set the units limits control parameters etc to the desired values before creating a program Number of Set points Before entering the sequence the user should determine the number of upscale and downscale set points required to complete the exercise Set point Pressure and Tolerance Each set point in the program requires both a pressure and a tolerance in the current units of measure For example one set point might require a tolerance as low as 0 05 psi 0 35 kPa whereas another set point in the same program could be satisfied with a tolerance as high as 5 psi 0 35 kPa Dwell Time Once the pressure is within the specified tolerance the DPC starts a timer that runs for a user defined number of seconds This is referred to as dwell time As long as this timer is running the DPC will remain at the designated set point unless the max time see below elapses When the dwell time expires the DPC will proceed to the next step Typically the dwell time should be set to a value less than the max time Usually dwell time has a value of a few seconds but a value of 0 can be used to create a pause in the program When the dwell time is set to zero the DPC switches to manual control once it is within the tolerance value of the set point pressure The user must then press a key on the front panel to continue the program
113. oint Step Press Enter to Confirm MAIN MENU Step 9 Press ENTER to accept the new set point The DPC will move to the new 5 point Step 10 Press Measure key which is located in the key pad The DPC will change to Measure mode No confirmation is necessary to leave Control mode 4 1 1 SELECTING LANGUAGE The 7250sys DPC can operate in a variety of different languages To select a different language press and hold the MODE key for 5 seconds The current language will be highlighted Use the rotary knob to highlight a new language and hit the ENTER key to select that language 4 1 2 SELECTING MODE OF OPERATION LOCAL OPERATION 4 6 The 7250sys DPC can operate in gauge or absolute modes 4 1 2 1 Simulated Absolute Instruments This 7250sys DPC sensor s operate in Gauge and Vacuum Negative Gauge modes and include a barometric reference sensor to monitor the barometric pressure The summation of the pressure reading the measurement sensor in the 7250sys and the pressure reading from the barometric sensor provides for the simulated absolute pressure display To change mode from the keypad press Mode then select either Absolute F1 or Gauge F2 Alternatively you can press MENU MODE to get to this menu Absolute Gauge MODE MENU 4 2 MAIN MENU The Main Menu displays the measured pressure in double sized numbers Below the pressure reading is the current unit of measure and mode Gauge Differ
114. old environment and the oven duty cycle is at a high percentage 29096 you will need to turn the fan off If you are operating a warm environment or when multiple systems are housed in consoles without adequate ventilation the system may become too hot and generate the oven control failure error message lf operating the instrument in a warm environment and the oven duty cycle is at a low percentage gt 10 you will need to turn the fan on When the operator changes the status of the fan it will default to that condition until it is changed by the operator MAINTENANCE 6 18 1 AAA bed E _ psi Diff Setpoint 0 00 DIZ Test Closed DI6 Zero Closed 015 Low Closed 04 03 012 DIO MENU TEST SHOP 1 MENU To turn the fan on or off press Menu F6 from the Main Menu then Test F5 then Shop F5 Use the rotary knob to highlight either fan Off or On Press ENTER to select 6 8 SYSTEM SOFTWARE UPDATE PROCEDURE NOTE Calibration and other stored constants are not affected by program updates The update procedure requires a PC connected to the RS 232 port on the 7XXX 9 pin to 9 pin null modem cable minimum pinout 2 3 3 2 5 5 1 When appropriate Ruska can e mail the latest version of the software for upgrading instruments The e mail will have a zip file attached contains two files UPDATE7 EXE and version Unzip these files into a directory on the 2 Se
115. ontents remain intact and damage free The foam cradle ensures that a minimum of 3 inches of foam separates the inner surface of the box and any portion of the DPC Wood or metal boxes do not absorb shock when dropped and therefore are not recommended The DPC must be prepared for shipment in the following manner 1 Ruska Instrument has an RMA procedure in place Please contact the Customer Service Center to obtain an RMA number prior to returning any equipment to Ruska Have the following information available when contacting Rusko d the part number 7 1 SIORAGE amp SHIPMENT 7 3 the serial number the purchase order number the billing and ship to address and the buyer s name and telephone number o This information plus the RMA number must be attached to the unit when it is shipped to Ruska Instrument There will be a minimal charge for inspection and or evaluation of returned goods Enclose the DPC in plastic or any good water barrier material Antistatic material is recommended For shipping the individual controller components use double walled corrugated carton with 275 16 rating The recommended carton size is 25 1 2 x 19 1 2 x 12 3 8 inches Insert one foam cradle from the original shipment onto the floor of the box The original foam cradles are of the same type of construction and are completely interchangeable It the foam cradles are not available cover the bottom and sides with
116. open the test port to the atmosphere In measure mode the DPC will indicate the variations A good filter may be usable in place of the valve if it provides approximately the correct restriction of air flow One consideration is that if the reference port is completely sealed from atmosphere its pressure will change due to barometric pressure changes or temperature changes in the environment If the pressure in the reference port becomes lower than the barometric pressure then a vacuum pump would need to be attached to the exhaust port to allow the controller to control down close to O psig For systems that have a barometric reference sensor option the barometer is tied to the reference port When operating in the gauge mode the reference port should be connected as noted above When operating in the absolute mode sealing the reference port from atmosphere will improve the stability of the DPC 3 5 5 VACUUM SENSOR OPTION The DPC is also available with a vacuum sensor option On DPC ranges that have the Evacuated Reference Option the vacuum sensor is used to monitor the vacuum level in the reference port when the reference port is pulled to a hard vacuum allowing the DPC to operate in the absolute mode INSTALLATION 3 4 SECTION 4 0 LOCAL OPERATION This section of the manual describes operation of the DPC using the front panel The local interface front panel consists of a color TFT display a rotary knob and a set of keys The displ
117. or F Gas Temperature TEMPerature2 Sensor A Oven Temperature TEMPerature12 Sensor B Oven Temperature TEMPerature22 Sensor C Oven Temperature TEMPerature32 Sensor D Oven Temperature TEMPerature42 Sensor E Oven Temperature TEMPerature52 Sensor F Oven Temperature VALue n number Perform calibration point DATA POINtS return number of calibration constants VALue n returns label value C0 0 123 VALue n number sets calibration constant CALibration VALue n 2 return nominal calibration point POINtS return number of calibration points number Zero sensor REMOTE OPERATION 5 6 DISP ENABle 1 0 lt text gt PRESsure BGRaph number OUTPut PRESsure STATe 110 MEASure CONTrol VENT PROGram CATalog SELected DEFine program block turns front panel display on off display message on front panel bar graph maximum off MEASure on CONTrol sets mode returns list of defined programs lt step press toler dwell max gt press1 toler1 dwell1 max1 press2 toler2 dwell2 max2 DELete SELected ALL program name gt STATe RUN PAUSe STOP CONTinue CONFigure SAVE SENSE PRESSure RESolution number AUTO ONCE deletes current program deletes all programs select current program change program state load program configuration save current configuration into progra
118. ort SCPI Standard Commands for Programmable Instruments The IEEE 488 interface additionally supports emulation of a Ruska Single Channel Interface Panel Models 6005 701 and 6005 761 The IEEE 488 interface contorms to the following standards ANSI IEEE Std 488 1 1987 IEEE Standard Digital Interface for Programmable Instrumentation ANSI IEEE Std 488 2 1987 IEEE Standard Codes Formats Protocols CommonCommands SCPI 1991 0 Standard Commands for Programmable Instruments 5 1 1 IEEE 488 The following identification codes define the interface capabilities of the DPC Identification codes are described in the IEEE 488 standard SH1 Source Handshake Complete Capability Acceptor Handshake Complete Capability T5 Talker L3 Listener SRI Service Request Complete Capability RL1 Remote Local Complete Capability PPO Parallel Poll No Capability DC Device Clear Complete Capability DTO Device Trigger No Capability CO Controller No Capability The IEEE 488 interface is installed next to the processor board The interface is identified by the IEEE 488 standard connector on the back panel of the unit 5 1 2 RS 232 The RS 232 interface supports standard serial operation from a computer to a single DPC 5 232 supports IEEE 488 2 and SCPI commands The DPC allows the following port setups Baud Rate 1200 2400 9600 or 19200 Data Bits or 8 Parity Even Odd or None Stop Bits 2 Handshaking XON X
119. ower and remove the instrument cover See Section 6 3 2 2 Remove the processor card by removing the screw and the bracket that locks the display cable in place and gently rock the card upward 3 Holding the processor card remove the battery the round silver object by carefully pulling on the battery 4 Plug in a new battery RIC 4 725 5 Reinstall the processor card the bracket that locks the display cable in place and the screw Replace the instrument cover 6 The time and date may have to be re entered See Section 4 6 1 5 6 4 CALIBRATION To keep the DPC operating within its specified precision the calibration procedure described below should be performed once every year f a higher level of overall performance is desired the user can calibrate more frequently NOTE The calibration procedure automatically generates coefficients that are stored in memory on the DPC s f these constants are lost for any reason the calibration procedure must be performed regardless of the last calibration date If the calibration coefficients have been recorded they may be restored to the DPC at any time by editing the coefficients Section 6 4 3 6 4 1 CALIBRATION INSTRUCTIONS To calibrate the DPC the user connects a calibration standard such as the Ruska Instrument Model 2465 or 2470 tor high pressure ranges Gas Piston Gauge to the 5 test port then follows the multi step calibration procedure on the DPC s display
120. pad will be cleared Step Jog _ Setpoint MAIN MENU 4 5 LOCAL OPERATION Step 5 When the entry is correct press the ENTER key The scratchpad will be cleared and the value will appear as the new set point Step 6 Now that the starting pressure is entered enter Control mode Press Control the F2 key The CONTROL label will be highlight and the message Press Enter to Contirm will appear below the scratch pad Notice that the upper left corner still shows MEASURE The DPC stays in Measure mode until the change Is confirmed Step 7 Press ENTER to confirm the mode change The upper left corner will change to CONTROL and the pressure will start moving towards the set point Step 8 After the pressure is stabilized assure that the word Step is highlighted in the Step Jog the F5 key The Step Jog the F5 key toggles between Step and Jog to switch between these modes press the function key 5 F5 In addition to using the key pad to enter a pressure set point you can also use the step function Using the rotary knob rotate the knob clock wise to increase the set point or counter clock wise to decrease the controller set point The scratchpad will be updated with a new set point The step size defaults to 1096 of full scale This step size is user defined and can be changed in the Menu Setup User menu Measure Control md v dh d Setpoint 100 00 Difference 10 00 Step Jog Setp
121. pad as the new name of the program 4 6 3 5 Changing an Existing Program Instructions for changing an existing sequence are given below Both manually and automatically generated programs may be edited 1 Programs are changed from the Program Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Program F4 2 Use the rotary knob to highlight the name of the program 3 Press Edit FA The program editing screen will appear as a table showing all of the steps Program 1 Cycles 1 Pressure Tolerance Dwell Max psi psi Sec sec 0 0000 0 0010 100 20 0000 0 0010 100 40 0000 0 0010 100 60 0000 0 0010 100 80 0000 0 0010 100 100 0000 0 0010 100 50 0000 0 0010 100 0 0000 0 0010 100 0 0000 CD 1 2 3 4 6 8 0 MENU PROGRAM EDIT MENU 4 The rotary knob can be used to move through the program and highlight the value you wish to edit Use the keyboard to enter a new value This value will LOCAL OPERATION 4 24 6 7 show up in the scratch pad located at the bottom of the window Press Enter to accept the edited value To add a step to the program first move to the step after the new step For example to insert a step between steps 3 and 4 move to step 4 Press Insert F4 To delete a step in the program first move to the step to be deleted then press Delete F5 When all changes have been made press PREVIOUS to return to
122. pecification The manufacturer may define Accuracy as the performance specification which consist only of item 1 above The result would be that the instrument would not be capable of meeting the users application because it would not meet the users definition of Accuracy 1 2 LONG TERM STABILITY defines how the instrument drifts with time This specification can be utilized to define the calibration interval for the standard Some manufacturers will provide more than one stability specification for their instrument based on different calibration time intervals It is important to understand that you should not arbitrarily vary the manufacturers stability specification based on time without knowing the characteristics of their device Some manufacturers identify that their stability specification is proportional with time Therefore if the calibration interval were reduced in half the magnitude of the stability specification would also be halved This can be a powertul tool when you are trying to improve the measurement performance of a standard By reducing the calibration interval the expanded uncertainty would also reduce On the other hand some manufacturers do not claim that their stability specification is proportional with time This would be the case for instance if the instrument naturally drifted in a sinusoidal fashion This would suggest that the sensor 1 APPENDIX A could drift to its maximum stability limit at any time and th
123. pply this pressure using calibration standard and follow the instructions in Step 2 3 entering the actual pressure applied 3 2 Repeat this procedure until all of the calibration steps are complete Review the Adj FS field to see if one point has a significantly higher adjustment required than other points in the calibration This may indicate that there was an error that specific calibration point The operator can re check this pressure point prior to completing and accepting the full calibration To re enter a point use the rotary knob and move the highlighted curser to the actual pressure values in the step in question Generate the requested apply pressure using the standard and enter then new actual value when stabilized 6 4 1 2 Storing the Coefficients Step 4 4 1 Calibration is complete To exit the calibration procedure without storing the calibration coefficients in memory press CANCEL To store the calibration coefficients in memory select the Done F1 key and the DPC will calculate all of its new coefficients NOTE In additional to saving the calibration coefficients to the DPC s memory the user is advised to separately record the calibration coefficients and store this backup in a safe place Step 5 5 1 Press PREVIOUS to return to the Main Menu 5 2 Once the calibration procedure is complete the user should verify several pressure readings against the pressure standard If there are variances beyond the
124. pressures using the rotary knob move the highlighted curser down to the first positive pressure step and generate all of the positive pressures in the procedure When you are complete with the positive points hit the Done key the unit will maintain the older coefficients for the negative gauge portion of the sensor and calculate new coefficients for the positive gauge ranges Conversely you can calibrate just the negative gauge section if desired However you must complete all of the positive or negative gauge steps in the procedure to complete a valid calibration 2 3 Using your calibration standard generate the pressure shown in the Apply column When the measured pressure stabilizes use the DPC s numeric keypad to enter the actual pressure applied by the calibration standard and then press ENTER Do not enter the measured pressure reported by the DPC If necessary use the CLEAR key to correct a mistake in the edit field 6 5 MAINTENANCE If the actual pressure applied is within the indicated tolerance the unit will accept that point and the highlighted curser will automatically scroll down to the next calibration step NOTE f the actual pressure is outside of the tolerance for the requested mid point pressure Error 222 Data out of range will occur Acknowledge this error by selecting OK F6 then re enter the actual pressure repeating step 2 1 if 3 1 Generate the next pressure calibration point requested by the DPC A
125. pump to pull a hard vacuum on the Ruska sensor It is recommend that the sensor P MAINTENANCE 6 12 be pulled down to a vacuum of less than 200 mTorr preferably less than 100 mTorr in order to obtain a proper zero The DPC can be zeroed at higher vacuum levels however the uncertainty of vacuum sensors tend to increase at higher vacuum levels therefore the uncertainty in the DPC would also increase if zeroed at higher vacuum levels 5 Wait for the vacuum level on the test port to stabilize 6 The vacuum level as read by the vacuum gauge will be displayed once stable and at an acceptable level press OK F6 7 Do not disturb the instrument while zeroing is in process 8 Wait for the zeroing procedure to finish 9 Press PREVIOUS to return to the Main Menu 6 4 6 3 Simulated Absolute Instruments Simulated absolute DPC s contain two sensors that require periodic zeroing The primary sensor is zeroed according to the instructions in Section 6 4 5 1 or 6 4 5 2 barometric sensor is zeroed according to the following instructions 1 Verify that the Reference Port is open to atmosphere 2 Enter the Calibration screen by selecting MENU CALIBRATE 3 Select the Atmospheric Sensor by pressing the Sensor F6 key until the words Atmospheric Sensor is displayed above the calibration coefficients 4 To begin the zeroing process press ZERO If the calibration access code is enabled enter it at the prompt The z
126. rate multiple ranges such as the 7250sys three calibration points are required per sensor range Automatic Zero Adjust At the user s request the DPC s software automatically performs the zero adjustment with no potentiometers to tune Automatic Head Correction The DPC automatically corrects for head pressure between the DPC and the device under test DUT taking into account the density of the lest gas e g air or nitrogen Choice of Medium Although the DPC is not sensitive to the type of gas used within the system the user can select either instrumentation air or nitrogen allowing the DPC to automatically make pressure head corrections Choice of Display Units Standard units include inHg at and 60 F kiloPascals bars psi inH O at 4 C 20 C and 25 C kilograms per square centimeter mmHg cmHg at 0 C and cmH O at 4 C Altitude and airspeed units include feet meters knots and kilometers per hour In addition to these predefined units four user defined units are programmable Communications Interface The DPC includes standard RS 232 serial and IEEE 488 interfaces The user s computer communicates with the DPC through the Standard Commands for Programmable Instruments SCPI protocol INTRODUCTION 1 2 1 4 STANDARD EQUIPMENT amp OPTIONS A standard DPC includes this manual and a power cord The components in the system are mounted in either a table top cabinet or stand up roll around cabinet Although the st
127. re This calibration requires the generation of two pressures within the range of 50 to 350 mtorr absolute The selected pressures should be spaced as far apart as possible within the allowable range Generate the first pressure Enter the actual value of the applied pressure generated by the standard and press ENTER Generate the second pressure Enter the actual value of the applied pressure generated by the standard and press ENTER 6 9 MAINTENANCE 12 13 14 6 4 5 The Vacuum sensor is now linearly compensated Once calibration procedure is complete the user should verity several pressure readings against the pressure standard If there are variances beyond the stated precision then an error was probably made in generating one of the calibration pressures and the calibration procedure should be repeated If the instrument is fitted with two vacuum sensor calibrate the second vacuum sensor Remove the vacuum standard from the instrument Reinstall the cover onto the 7250sys EDITING THE CALIBRATION COEFFICIENTS If the DPC s memory is erased but the calibration coefficients are known the user can restore CAU the coefficients to the DPC by following the directions below TION Never randomly adjust the calibration coefficients Only qualified personnel with valid backup data should be allowed to edit the coefficients If the backup coefficients are questionable perform the calibration procedure i
128. ries to limit the rate of pressure change to the slew rate 4 6 1 1 8 Slew Limit The slew limit is used by the system to assure that the slew rate 15 not exceeded If the slew rate is exceeded the DPC will change from the control mode to the measure mode and it will generate an error message to the operator 4 6 1 1 9 Access The test access password allows the user to protect access to DPC contiguration and programs If the test access password is set to any number other than zero factory default it is required before the user is allowed to change the limits control parameters or programs IMPORTANT It is recommended that the access password be recorded and filed in a secure location 4 6 1 2 Menu Setup User The Menu Setup User menu is used to setup all of the user specific configurations This includes setting the control step size range of bar graph pressure gas head display pressure filter display resolution digits and audible key click The step size bar graph max ready tolerance and gas head are defined separately for each channel All other entries are common for both channels 10 00 psi Bargraph Max 100 00 psi Ready Tolerance 0 01 psi Gas Head 0 0 mm above 250x Atmosphere 101 325 kPa Pressure Filter 4 019 0 1 Key Click Yes Menu Setup User Menu 4 6 1 2 1 Step Size In addition to entering the pressure set point by the key pad the pressure set point can be changed u
129. sing the step function The step function is used primarily when the operator is taking pressure steps in equal pressure increments The size of the pressure step is user defined From the Main Menu press Menu F6 Setup 4 13 LOCAL OPERATION F2 and then User F2 Using the rotary knob move the cursor to highlight Step Size Enter the desired step size in the current pressure units and press ENTER 4 6 1 2 2 Bar Graph Maximum The bar graph the Main Menu screen can be scaled to match the device under test by setting the full scale value of the bar graph 4 6 1 2 3 Ready Tolerance A Ready indication is generated when in control mode and the measured pressure is reading within this ready tolerance value When running an internal program the ready indicator is shown when the measured pressure 15 within the tolerance stored in the program 4 6 1 2 4 Gas Head Pressure Correction The term head height refers to the vertical distance between the sensing element in the device under test and the DPC s pressure reference plane Once the user inputs the head height and selects air or nitrogen the DPC automatically corrects tor head pressure 1 The Pressure Reference Line on the DPC is defined as the bottom of the color display where the display and the panel join This provides the reference plane against which the device under test DUT pressure is measured 2 Determine the vertical distance between the DPC Pressure
130. ssure Enter Zero Mode Ej write 7000 p En wart for calibration values to be within Limits 7 jc CATE ZEROS INIT ir B amp do t 5 72 getch break request 7000 CAC ZEROS sscanf buffer d d d d amp cstat amp pstat amp tstat amp rstat Lr Check errors 29 ret rm 19 goroxy 205 5ys if pstat 0 Staple er else Xr porat 0 printi Out of Range else if pstat gt 0 cprintf Unstable 2d seconds pstat Gouoxy 20 7 26 2 if tstat 0 Stable else if tstat lt 0 cprintf Out of Range else if tstat 0 cprintf Unstable 2d minutes tstat 20 T if rstat 0 printi Stable else if rstat lt 0 cprintf Out of Range else xr estat gt Oy printf Unstable 524 seconds Estat 5 15 REMOTE OPERATION Whale pstet f 0 fi 0 He Start Zero Adjust CAL ZERO RUN e write 7000 RUN NYS a Wait for zero to complete ys COND request 7000 STAT OPER COND n sscanf buffer Sd amp status LE
131. st vent the bell jar vacuum towards atmosphere until the masses begin to float Close the metering valve as soon as the masses begin to float Open the bell jar cutoff valve to the test port of the DUT close the exhaust Vent valve and use the pressure adjuster handwheel to adjust float position of the deadweight gauge to float the piston at mid float position 6 4 3 RPT CALIBRATION SIMULATED ABSOLUTE A span correction can be applied to the RPT barometric sensor This correction is done using the DPC software and can be performed without removing the RPT from the DPC chassis 1 Place the DPC in Measure mode Remove all pressure sources from the system 2 Connect a pressure standard to the Reference Port of the DPC Note on the 7 250sys there are two reference ports Typically the RPT is connected to the top reference port However this can vary based on the configuration of the 7250sys If the barometric sensor does not react when changing the pressure in the top reference port try the lower reference port 3 If desired change the DPC s units of measure see Section 4 to match those of the calibration standard 4 To access the Calibration screen the Menu select MENU CALIBRATE CALIBRATE 5 Select the atmospheric sensor by pressing the Sensor F6 key until the words Atmospheric Sensor is displayed above the calibration coefficients To begin the calibration process press CALIBRATE f the calibr
132. sure Control Pressure control is performed by a dual loop control system The inner loop is a digital loop using a high trequency response silicon strain gauge sensor a digital controller and two pulse width modulated solenoids The two solenoids either add gas to the test port or remove it The outer loop provides closed loop control based on feedback trom the quartz Bourdon tube and an analog output setting which provides the desired set point for the inner loop The 72505 5 incorporates multiple controllers into the design and automatically switches between the controllers to provide the optimum control performance based on the pressure set point 2 5 CONTROL STRATEGY 2 5 1 INNER VS OUTER LOOPS The inner loop accepts a signal from the outer loop and uses this signal as the pressure set point The inner loop uses a high frequency response strain gauge sensor as its reference The frequency response of this transducer allows for high speed modulation of the solenoids This sensor is aligned to the high accuracy quartz sensor when the system is Auto tuned The outer loop is a lower frequency response analog digital loop The outer loop uses a calibrated forced balanced sensor This sensor is used to monitor the pressure of the system The results are used for the displayed pressure The outer loop is responsible for adjusting the signal sent to the inner loop to compensate for temperature and time drifts associated with the inner loop sensor
133. t Exceeded The pressure was greater than the high limit Low Limit Exceeded The pressure was less that the low limit Slew limit Exceeded The pressure changed faster than the slew limit allowed Pressure Overrange The pressure reading is outside the range of the DPC Oven Temp Overrange Either the transistor that drives the heater for the quartz Bourdon tube sensor section 2 or the oven temperature sensor itself is malfunctioning To observe the oven temperature select OK then select MENU DISP Check the transistor and sensor for malfunction requesting service 330 350 400 500 501 502 503 531 1 APPENDIX section 7 if necessary Case Pressure Overrange Select OK then reduce the pressure at the case 5 5 5 5 reference port to 30 psia or lower Automatic Vent Pressure exceeded the Auto Vent limit Mechanical Zeroing Needed The zero point of the quartz Bourdon sensor is beyond the range of the compensation circuit The zero is adjusted by the sottware but should be manually adjusted for complete accuracy Oven Control Failure The temperature controller is unable to keep the sensor at the proper temperature 545 Sensor Communication Error Unable to Communicate with 7215xi Sensor 546 Sensor Calibration Lost The 7215xi sensor has lost its calibration and must be recalibrated Factory Data Lost Internal factory constants have been lost Contact Ruska tor more information 6 Calibr
134. t four digit year month and day yyyymmdd All digits must be entered Press ENTER to accept 3 To set the system time turn the rotary knob until Time is highlighted Use the numeric keypad to enter the current hour minute and second hhmmss All digits must be entered Press ENTER to accept 4 6 1 5 2 Reset The Reset F1 command is used to re boot the DPC 1 To reset the system from the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 then System F5 and then Reset F1 4 6 2 MENU CALIBRATE The Menu Calibrate command is used to perform the calibrations on all of the sensors utilized by the DPC The 7250sys can be completely calibrated using the front panel interface t does not require any external computer or software in order to perform a successful calibration It also has the capability of being calibrated remotely through either the RS232 or IEEE 488 interface The 7250sys will guide the operator through a menu driven calibration procedure identifying the pressures that should be supplied by a standard Following the calibration procedure the 7250sys calculates and saves its own coefficients The calibration coefficients are date stamped so the user can easily identify the last time the instrument went through a full calibration when the coefficients were last edited or when the DPC was re zeroed The calibration section in the DPC can be password protected to prevent any
135. t prior to performing a calibration sweep test input the high and low set point pressures the pressure control tolerance the dwell time at set point and the number of cycles to perform 1 2 sweep test is entered from the Sweep Test Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Test F5 and then Sweep F2 Enter the high and low pressure points the control tolerance dwell time and the number of cycles 4 Ensure that the units limits and control parameters are to their desired values int 0 00 Sweep Cycle 0 Timer Pressure Low psi Pressure High 0 00 Continue Tolerance 0 00 Dwell 0 Cycles MENU TEST SWEEP MENU Press Run F2 to initiate the test 5 To pause the program press Pause F3 Pause will now be highlighted and the DPC will continue controlling to the current set point control of the current set point until further instructions from the user Continue F4 to resume the program 4 27 For the DPC to perform the The DPC will maintain LOCAL OPERATION 6 To stop the program press Stop F5 The program will stop running but the DPC will continue controlling to the current set point 4 6 4 2 Menu Test Self Test The DPC can perform electrical and pneumatic self test to assist in trouble shooting potential problems Please refer to the Maintenance Section 6 0 for more details NOTE In order to
136. t the 7XXX to 9600 baud 8 databits no parity 1 stopbit 3 Run the program Update7 4 Follow the prompts to select the communications port and the image file 5 When the upgrade is finished Update7 running on the PC and the 7XXX should both display Complete 6 8 1 Model 7250sys Controller Software Upgrade In addition to the main code the 7250sys include code for the pressure controller The controller software version can be viewed by pressing the MENU TEST REMOTE SERIAL2 keys The controller software version is displayed next to Ctrl This code can be upgraded through the RS 232 port on most units Press the MENU TEST CONTROL key and check for Download Yes IF Download is displayed the chip must be replaced to upgrade software Download is not displayed upgrade the main software to 7250sys 1R17 or higher first The digit in front of the R increases with revision levels and the last two digits will increment upwards as the revision level increases e g OR99 is older code than 1 01 which is older than etc 6 19 MAINTENANCE 1 Connect a PC to the 5 232 port on the 7XXX using a null modem cable 2 The zip labeled 7250sys Control XRXX contains files UPDATE7 EXE and lt version gt IMG Unzip these files into a directory 3 Set the 7XXX to 9600 baud 8 databits no parity 1 stopbit 4 Run the program Update7 5 Follow the prompts to select the communications port an
137. tactors are given in Table 2 1 Data that is subject to change after the DPC leaves the factory are held in electrically erasable programmable read only memory EEPROM This includes the current units of measure the coefficients from the zeroing process the current pressure medium calibration coefficients and the conversion factors for the four user defined units of measure When the DPC powers up its software is loaded into random access memory RAM also on the Microprocessor Board At the same time the values stored in EEPROM Board are restored to memory Another important component on the Microprocessor Board is the lithium battery The battery continuously updates the DPC s date and time even when the unit is powered down This battery has a varying life If the instrument is left on 24 hours a day it may last 5 to 10 years If the instrument is stored it may only last one year The Microprocessor Board also supports the RS 232 serial interface that allows the user s computer to communicate with the DPC THEORY OF OPERATION 2 2 user defined Pascals kPa x 1000 0 user defined hectoPascals kPa x 10 0 percent of full scale UNLESS SPECIFIED OTHERWISE CONVERSION FACTORS ARE BASED ON ANSI 268 1982 TABLE 2 1 CONVERSION FACTORS 2 3 3 DIGITAL CONTROL BOARD The Digital Control Board plugs directly into the Back plane Board This board reads a high speed silicon strain gauge pressure transducer PDCR
138. the Named programs screen The DPC automatically saves the changes that were made in the program 4 6 3 6 Changing the Configuration Stored with a Program 1 Programs contigured from the Program Menu From the Menu press PREVIOUS until the Main Menu appears press Menu F6 then Program 24 Use the rotary knob to highlight the name of the program Press Config F3 The configuration screen will appear Press Recall F2 The DPC will be set to the configuration stored with the program Program TESTO1 Configuration High Limit 110 000 psi Recall Low Limit 20 305 Control On Band 0 001 Control Off Band 0 000 Bargraph Max 100 000 Slew Rate 9999 997 psi min Slew Limit 9999 997 0 0 Control Normal Display Digits 1 Type MENU PROGRAM CONFIG MENU Press PREVIOUS until the Main Menu appears Press Setup F2 then Limits 1 Change the desired parameters using the normal procedures Return to the Main Menu by pressing PREVIOUS three times Press Menu F6 then Program F4 Use the rotary knob to highlight the name of the program Press Config F3 then Save F1 The configuration of the DPC will be changed to the current settings and stored in the program s configuration 4 6 3 7 Running a Program 4 25 LOCAL OPERATION 1 Programs are run from the Program Menu From the Main Menu press PREVIOUS until the Ma
139. the Normal control mode as opposed to the fast control mode the controller overshoots the commanded pressure valve this could be an indication that the inner loop control sensor needs to be realigned with the high accuracy quarts sensor This is achieved by running the Calibrate Auto Tune function NOTE Prior to performing any Auto Tune functions in an effort to improve the controller performance confirm that the system is a leak free system and the volume attached to the test port is within the recommended range see Appendix A Additionally assure that the system has adequate pressure and vacuum supply when required To perform these Auto Tune functions the instrument must be connected to a pressure supply with the pressure supply set to the proper supply pressure please refer to the specifications in Appendix A On absolute instruments a vacuum pump must be connected to the exhaust port Disconnect any device under test from the test port The test port must be connected to a sealed volume of 5 to 15 cubic inches 80 to 240 cc s Use the Rotary knob to select which Auto Tune procedure is to be performed and then press the enter key The Full performs the complete Auto Tune sequence If selected you are not required to run any of the other Auto Tune functions Press the enter key The DPC with go through a sequence of controlling to various pressures and automatically adjusting the control parameters of the valves The DPC
140. the real time clock Replace processor board 7215 586 3 Tests the 10 ms interval timer Replace processor board 7215 586 3 EEPROM Tests the nonvolatile memory Replace processor board 7215 586 3 Oven Tests operation of the sensor oven Replace sensor assy Contact Ruska Allow oven to warm up 6 3 2 REMOVING THE DPC S COVER The DPC should be kept clean and completely assembled at all times Operating the DPC without its cover affects the DPC s thermal gradients and therefore may reduce precision If it becomes necessary to remove the DPC s cover follow the instructions below CAUTION The DPC should only be opened by qualified electrical mechanical service technicians Lethal voltages are present and exposed in the power supply and display 1 Turn off the DPC and disconnect the power cord from the DPC 2 Locate and unscrew the tour screws that secure the cover to the back panel 3 Place your hands near the middle of the cover and slide the cover towards the DPC s back panel 4 Lift up on the cover With the cover removed use typical electronic cleaning tools to remove any accumulated dust from inside the instrument 5 Replace the cover before resuming operation 6 3 3 MOISTURE FILTER The Bourdon tube sensor is hydroscopic An external desiccant filter prevents introduction of moisture and is strongly recommended for high humidity areas The filter should be replaced annually The moisture filter is used with the re
141. there are multiple supply pressure ports one for each pneumatic control module On a standard cart system a separate regulated pressure supply is connected to each individual supply pressure ports On the table top version of the system each control module must be supplied with its individual regulated supply pressure 2 4 2 2 Vacuum Supply Exhaust Port For many applications a vacuum pump is not necessary The Exhaust Port includes a solenoid valve that is open only when the DPC is controlling pressure In Gauge mode if the DPC will not be used to control pressures at or very near atmospheric pressure then the Exhaust Port should simply be left open to atmosphere Likewise in Absolute mode if the DPC will not be used to control pressures at or below atmospheric pressure the same rule would apply However if the DPC will be required to control to atmosphere in Gauge mode or sub atmospheric pressures in Absolute mode then a vacuum pump must be connected to the Exhaust Port Select a vacuum pump with the test port volumes and system slew rates in consideration The minimum requirements are noted in Appendix A The vacuum pump is an optional accessory in the standard cart system When the absolute mode with evacuated reference option is selected the system must be configured with two vacuum pumps one used to control sub atmospheric pressures and the second to evacuate the sensor reference ports THEORY OF OPERATION 2 6 2 4 2 3 Pres
142. to control sub atmospheric pressures then a second vacuum pump 2 5 THEORY OF OPERATION should be connected to the exhaust port for use in pressure control It is recommended to use one pump connected to both the reference and the exhaust when operating in absolute mode since the controller could cause an unstable reference vacuum 2 4 1 2 Test Port The Test Port connects the DUT to the Pneumatics Module The system automatically switches between the various sensor ranges within the system when controlling pressure selecting the most accurate sensor in the system to monitor the pressure A relief valve protects each sensor in the system 2 4 1 3 Vent Procedure The vent mode is implemented with a fast multi step procedure For gauge instruments the DPC controls pressure at the maximum rate towards zero psig When the primary sensor reads that the pressure is within 1 FS pressure of zero psig the controller is turned off and the reference zeroing solenoid is opened which vents the remaining test port pressure to atmosphere If the DPC is at a sub atmospheric pressure then the system will control to zero psig at maximum rate turn off the controller and open the zeroing solenoid 2 4 2 CONTROL MODE PNEUMATICS 2 4 2 1 Pressure Supply Port The Pressure Supply Port connects the user s regulated gas supply to the Pneumatics Module Please refer to Appendix for gas specifications and supply pressure limits On the 7250sys
143. trlen s rora device buffer Srzeotft 5 6 3 SAMPLE PROGRAM 3 7252 SERIAL RS 232 CONTROLS PRESSURE TO 20 000 FS C T E UE x Sample Program 3 7252 Serial RS 232 mU um ot Controls pressure to 20 000 5 5 E include lt stdio h gt include lt stdlib h gt include lt conio h gt include lt dos h gt include lt time h gt define TRUE 1 define FALSE 0 define TIMEOUT CLK 5 5 second timeout 0x11 XOFF 0x13 fdefine CLEAR 0x03 derine DLE Qxlo define QUEUE SIZE 1024 char buffer QUEUE SIZE for input output Strings 7 double pressure Pressure read from unit int status Status register from unit int address int portbase int mers Volquile 206 enabled TRUE char anqueue QUEUE SIZE int Lng xm int Ing out rnterr pt orld vector 97 rnit Check errors 5 17 REMOTE OPERATION VOid serial initialize void werte 1000 serial Char 9 7 void serial close void 7000 Sex void serial write char s char ch Nee ne void main void Char eps TR x Initialize Serial Interface rd TP x address 4 Anata lize 272 eee eee ae eee ee eee eee eae initialize 7252
144. will display a 6 17 MAINTENANCE message indicating when it is complete with the Auto Tune procedure The time required to complete the Auto tune procedure can range anywhere from 15 to 45 minutes AutoTune State 2 Inner 0 00 A Bias Setpoint 0 000 4 Control 0 R Bias Rate 0 R Adj Apply 0 Release 0 If any control valves or the high speed inner loop pressure sensor has been replaced the Auto Tune should be run to characterize the new hardware 6 7 FAN OPERATION The fan in the 7250sys can be turned on or off It is recommended to keep the fan ON since this will extend the life of the power supply When operating the system in either a very cold or hot environment if the oven is unable to maintain the temperature of the internal oven it will generate error Oven Control Failure Error messages The operator can review the temperature and duty cycle of the oven by pressing the MENU DISPLAY TEMPERATURE keys The unit must have been warmed up for a minimum of 2 hours prior to determining the condition of the oven temperature control The temperature of the sensor should be controlled to 50 C The Duty cycle indicates the percentage of time that the oven control is turned on in order to maintain the oven at the proper set point of 50 C A unit that is operating properly after it has fully warmed up should indicate a sensor temperature of 50 C and a duty cycle between 10 to 90 If operating the instrument in a very c
145. xceeding the high If the user enters value greater than the user detined limit the unit will not accept the value and it will generate an error code informing the user that they have entered a set point that is greater than the high pressure limit In control mode if for any reason the pressure exceeds the user defined limit it will change into the measure mode and again display an error message to the operator intorming them of the error that occurred This value can be edited using the rotary knob to highlight the High Limit Then enter the new value using the keypad This will show up in the scratch pad on the lower portion of the screen Press the Enter key and the value for the high limit will be updated to the value that was typed into the scratchpad 4 6 1 1 2 Low Limit User defined Minimum pressure limit This is the same as the high limit except it is to protect the DUT from low pressure limits 4 6 1 1 3 Auto Vent User defined maximum pressure that the DPC can reach prior to venting the test port to atmosphere 4 6 1 1 4 Control Band There are two common pressure control approaches that are available with the Ruska 7250sys DPC One of the most common control styles is an Active controller where the controller remains operative and holds the pressure at a commanded set point This allows the system to hold the pressure at a set point within the control stability specification See Appendix A In addition to possible
146. yboard The command DISPLAY ENABLE ON will restore the local display and keyboard operation Local operation may also be restored by turning the DPC off and back on 5 3 CONFIGURATION The remote interface must be configured before it is connected The remote interface is configured using the local interface The parameters needed vary with the interface used IEEE 488 Address Protocol RS 232 Baud Rate Dota Bits Parity Stop Bits To configure the remote interface 1 The remote interface is configured from the Setup Remote Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 and finally Remote F4 2 Use the rotary knob to highlight the desired parameter 3 Use the numeric keypad to enter the address use the rotary knob to change the other parameters The ENTER key must be pressed after entering the address REMOTE OPERATION 5 2 4 Repeat steps 2 and 3 to set all parameters needed 5 4 DEVICE MESSAGES 5 4 1 COMMAND FORMAT SCPI mnemonics have two forms long and short The short form is all in capital letters The long form is the entire mnemonic Commands may use either the short torm or the entire long form No other forms are accepted SCPI ignores case uppercase and lowercase are equivalent A SCPI command is made by following the command tree as presented in the command summary Each level adds a mnemonic to the command separated by colons M
147. yed on the front panel of the 7250 controller 4 4 VENT The Vent F3 function is used to rapidly vent the pressure in the system to atmosphere This system does not have a designated internal vent valve Instead the vent mode is implemented with a fast multi step procedure For gauge instruments the DPC controls pressure at the maximum rate towards zero psig When the primary sensor reads that the pressure 15 within 1 FS pressure of zero psig the controller is turned off and the zero solenoid valve that ties the reference port to the test port is opened This physically vents the test port to atmosphere the DPC is at a sub atmospheric pressure then the system will control to zero psig at maximum rate turn off the controller and open the zeroing solenoid valve again venting the test port to atmosphere This function is not available on permanent absolute versions of the 7250sys 4 5 STEP JOG This feature is only available when operating in the single channel mode In addition to entering the pressure set point through the key pad the pressure set point can be changed using either the step or the jog tunctions The Step function is used primarily when the operator 15 taking pressure steps equal pressure increments The size of the pressure step is user defined The Jog function is most often used when calibrating mechanical gauges such as a dial gauge and the operator wishes to change the pressure until the mechanical gauge in
148. ystems have an integrated pressure intensifier option installed These systems require a nominal shop Air supply of 100 psi A clean dry nitrogen pressure supply is connected to the high pressure Gas supply port on the rear panel of the system This supply fills the accumulator in the system and then supplies the various regulators in the cart system which ultimately supply each individual control channel in the system The system can operate directly from the high pressure supply Additionally as long as a minimum supply pressure of 500 psi is available the intensifier can boost the accumulator pressure which supplies the system Turning the Driver Air valve clockwise to the on position turns the intensifier on The regulator directly below the Drive Air valve is used to adjust the maximum pressure that the intensifier boost the pressure to the accumulator All of the regulators in the system are preset at the factory 6 21 MAINTENANCE THIS PAGE INTENTIONALLY LEFT BLANK MAINTENANCE 6 22 SECTION 7 0 PREPARATION FOR STORAGE amp SHIPMENT NOTE The procedures given in sections 7 1 through 7 3 must be strictly adhered to in order to prevent damage to the instrument Failure to follow these procedures will likely result in damage to the DPC during shipment This damage is not covered by the carrier s insurance 7 1 DISCONNECTING THE DPC Relieve all pneumatic pressure from the DPC Turn the DPC power switch to t

DIGITAL PRESSURE CONTROLLER

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