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Contents
1. 14 1 10 3 CLEAR ALL STATUS REGISTERS 17 1 10 4 SERIAL POLL AND STATUS BYTE REGISTER 17 1 10 5 STANDARD EVENT STATUS REGISTER 18 1 10 6 THE OPERATIONAL REGISTERS 19 1 10 7 THE QUESTIONALBE 21 2 IHERS 232 INTERFACE orececaxcxciixennh odis basin anni erc ER ER ER anis ie 22 Document 83 468 007 Rev B 21 CONFIGURING THE RS 232 2 4 44 22 22 2 1 4 THE RS 232 CABLE depen aea eua 22 2 1 2 DEFAULT RS 232 CONFIGURATION eee 22 2 22 RS 232 COMMAND 24 2 2 1 CHANGE CHARACTER 24 2 2 2 TO LOCAL 1 25 22 3 CHANGE THE BAUD 25 2 24 CHANGE THE DATA 8 2 11 25 2 2 5 CHANGE THE PARITY BITS sss 26 2 2 6 CHANGE THE STOP BITS sse 26 2 3 ERROR REGISTERS AND RS 232 sesenta 27 3 ADJUST THE IEEE CALIBRATION eren 28 3 1 INTRODUCTION 28 3 2 CALIBRATE THE VOLTAGE2. 28 3 3 CALIBRATE THE VOLTAGE 30 34 CALIBRATE THE CURRENT PROGRAMMING 31 3 5 CALIBRATE THE CURRENT MEASUREMENT 32 4 SUMARY TABLE OF COMMANDS eene 35 List of Tables Table 1 The SAV 0 13 Table 2 The Status Byte 17 Table 3 The Standard Event Status Register 18 Table 4 Operational 19 Table 5 Default RS 232 Configuration 22 Table 6 RS 232 Echo Settings 24 List of Figures Figure 1 IEEE Address Switch Settings 3 Figure 2 Status and Error Register Diagram 15 Figure 3 Status and Error 16 Figure 4 RS 232 Cable Construction 23 Document 83 468 007 Rev B Introduction 1 WARNING When a power supply with IEEE option is first powered ON or when a Go To Local command is sent the supply output will jump to whatever is set on the front panel knobs Therefore it is recommended the front panel Voltage and Cur
3. USE 2 UU NSAS WHdO lVIS 20 UU HS logo Ene saa xa J931siboM 32 IM L JeysiDes snjejs Plepueys eur jsonbes 445 uu WuSx 25 1 4931siDoM o3 g snyeis pesn oan 9 5 1221607 aNd 8980 1415 uu WN dado 1415 a mew RI 318VN3 Ei 2 CeNSAH HNHdO LVIS p 14125 ____ 2 Query Error Power On gt Operation Complete Execution Error Command Error Not Calibrated 1 jno ueJ Jajsibay 3331 Over Voltage Over Current Status and Error Register Diagram Figure 2 Document 83 468 007 Rev B Error Registers 16 Initialize Error Registers Sample Error Handler SRE 240 ESE 180 Routine Suitable for Automation Programming OPER STAT ENAB 3 7 7 7 a 7 sar Send Command SERIAL POLL read Status Byte Last cmd end with Read Output Queue Bit 6 RQS Set Yes Bit 5 ESB Set No Bit 2 QUE Set Query
4. Save response message as Old SCRG gt 3 5 2 Measure supply output current Use IEEE card to measure output current by sending query MC and record the response message Calculate New SCRG gt Measured output current X Old SCRG gt Response to MC Send command SCRG New SCRG gt Repeat this until the response from the MC query is within 0 05 of the measured output current 3 5 3 ADJUST OFFSET VALUE Send command to set supply to 10 of its maximum current Maximum supply voltage gt PC lt Tenth of maximum supply current gt If it is not known read existing current offset value by sending query SCRO Save the response message as lt Old SCRO gt 3 5 4 Use IEEE card to measure output current by sending MC Record response message Measure the supply output current If the response to the MC query is higher than this measurement you have to choose a lower value for SCRO If the response message is lower choose a higher SCRO Picking the correct SCRO is a trial and error process It is typically 0 001 and it must be between 0 1 and 0 1 Send new calibration factor by sending command Document 83 468 007 Rev B 34 SCRO lt SCRO gt Repeat this step until the value returned from the MC query is within 0 05 of the measured output current 3 5 5 VERIFY CURRENT MEASUREMENT LINEARITY Program the supply to various current betwe
5. power supply output be shut off by sending this command SOURCE VOLTAGE OUTPUT OFF or VOLT OUT OFF This command will not disconnect the supply output It is equivalent to programming the output to zero volts To read if the supply output is disabled send query VOLT OUTP 0 zero will be returned if the output is disabled The short form for supply off is SF ENABLE THE SUPPLY OUTPUT After the supply output has been shut off with the SOUR VOLT OUTP OFF command the output can be turned back on by sending this command SOURCE VOLTAGE OUTPUT ON or VOLT OUTP ON The output will immediately jump to the last programmed voltage and current To read if the supply output is enabled send query VOLT OUTP A 1 one will be re turned if the output is enabled The short form for supply on is SN READ PROGRAMMING MODE The power supply may be programmed in two modes In Local Mode the front panel knobs or back panel analog connections set the supply output In Remote Mode the IEEE RS232 interface sets the output The mode is indicated by the front panel REMOTE LED if it is installed The mode may be read by sending this query SYSTEM PROGMODE or SYST PROG The response will be one of three choices LOCAL REMOTE OR FORCED LOCAL Since sending a query takes the supply out of Local Mode that response will not be re ceived The Forced Local Mode is set by the first rocker on the IEEE address switch see Figur
6. 3 Query for over current shutdown SOURCE CURRENT TRIPPED or CURR TRIP Read the response number The normal response is 0 zero If a 1 one is returned it means an over current has occurred and the output is shut down The response number is actually the value of the Operational Condition Register Bit 1 Because an over current can set bits in four IEEE registers it is recommended that a CLS be sent to clear them after an over current occurs See Section 0 on Status and Error Register Programming for more details The short form for set current protection tripped is SCPT 1 8 4 4 Reset after shutdown SOURCE CURRENT CLEAR or CURR CLE After an over current shut down has occurred this command must be sent to reset the error status before any new current commands will be accepted If and over current is not reset and a new current command is sent the command will be ignored and the Command Error bit in the Standard Event Status Register will be set The short form for set current protection clear is SCPC Document 83 468 007 Rev B Common Commands 12 1 9 1 9 1 1 9 2 1 9 3 1 9 4 COMMON COMMANDS READ DEVICE IDENTITY The IEEE spec requires that every instrument be able to report its identify to the control ler The query is IDN When the controller reads the output from the power supply a single line identity string will be returned A typical identity string format is LAM
7. Available in Output Que Set after query message is received Table 2 Status Byte Register 1 10 4 1 The Service Request Enable Register The Status Byte Register may be set so if an event causes bits 4 5 or 7 to go high then the Service Request may or may not be asserted The command to set the bits high in the enable register is SRE lt nn gt where lt nn gt is a number between zero and 255 A space is required before the number The power up default is all zeroes in the enable register This means no status or errors will be reported by the serial poll function Document 83 468 007 Rev B Error Registers 18 1 10 5 Typically the enable register will be initialized with SRE 160 set bits 5 and 7 This will enable a service request if an error occurs in the Standard Event Status Register or in the Operational Event Register The contents of the Service Request Enable Register may be queried by sending SRE The response will be a bit weighted number whose bits correspond to Table 2 Bit 6 the Service Request bit cannot be set It is always zero STANDARD EVENT STATUS REGISTER The Standard Event Status Register has eight bits that indicate status and errors for the power supply and the interface It is a very popular register An error in this register will illuminate the red error LED on the interface board Resetting this register will turn off the LED To read the contents of this register use the common
8. Error Detected Execution Error Detected Command Error Detected Power On Detected Bit 4 EXE Set Bit 5 CME Set Bit 7 PON Set Bit 7 OPR Set Over Voltage Detected Over Current Detected Figure 3 Status and Error Handler Bit 1 OC Set Document 83 468 007 Rev B Ertar telgesfisters 17 1 10 3 CLEAR ALL STATUS REGISTERS The contents of the status registers will be reset to zeroes by sending CLS This command will clear the Status Byte Register and the Event Registers It will not af fect the Conditional or the Enable registers After an error this command will also turn off the red error LED on the interface board 1 10 4 SERIAL POLL AND STATUS BYTE REGISTER The Status Byte Register contains three bits that are set when a condition occurs in any of three status registers If any of these three bits are set the Request Service RQS bit can become set The RQS bit is important because it will assert a signal onto the Ser vice Request SRQ line in the IEEE cable The controller program can detect the SRQ read what the problem is from the power supply and clear the SRQ The bit assignments for the Status Byte Register are Se NUMBER VALUE SYMBOL DESCRIPTION Status or error reported by Standard Event Status Register Request For Service Is set if any one of MAV ESB or OPR is enabled and set Over volt or over current error reported by Operational Event Register Message
9. are stored by the 5 0 command CAL IDN CAL DATE CAL LOCK AFV AFC SOUR VOLT AMPLITUDE SOUR CURR AMPLITUDE SOUR VOLT LIMIT SOUR CURR LIMIT SOUR VOLT LEVEL SOUR CURR LEVEL CAL SOUR VOLT SLOPE CAL SOUR CURR SLOPE CAL SOUR VOLT OFFSET CAL SOUR CURR OFFSET CAL MEAS VOLT GAIN CAL MEAS CURR GAIN CAL MEAS VOLT OFFSET CAL MEAS CURR OFFSET SYST COMM SERIAL BAUD SYST COMM SERIAL BITS SYST COMM SERIAL SBITS SYST COMM SERIAL PARITY ECHO EN or EF Table 1 The SAV 0 Command 1 10 USING ERROR AND STATUS REGISTERS Document 83 468 007 Rev B 14 1 10 1 OVERVIEW REGISTER FAN OUT The IEEE Interface board has a set of status and error registers They are defined by the IEEE 488 2 specification as part of the Common Command set required by all compliant instruments These registers allow the IEEE controller to examine the operational state of the supply in detail A fan out architecture is used so only one summary register needs to be read to know if an event occurred in any other register This fan out allows automatic test programs to efficiently manage the remote programming mode A diagram of the register structure is shown in Figure 2 This diagram does not show all the registers in the IEEE 488 2 specification It only shows the registers typically used in the Lambda power supply The algorithm for reading the register fan is part of a program device dr
10. difference between the MV response and the actual output voltage is less than 0 1 of the full output voltage If the error at any level is greater than 0 1 of full output then the voltage measure ment on the IEEE card is NOT calibrated If the IEEE measurement is NOT calibrated repeat procedure from step 3 3 1 to step 3 3 4 SAVE CALIBRATION FACTORS Enter commands 0 is zero not letter 0 0 SAV 0 CALIBRATE THE CURRENT PROGRAMMING Verify the load connected to the supply keeps it in current mode even when the current is set to maximum The load should not allow the voltage to exceed 90 of maximum voltage A cable may be connected across the output terminals shorted load but for best results use the load typical of your application Throughout this section references are made to lt Actual output current gt Since we cannot measure current directly the Actual output current is found by connecting an external shunt resister measuring the shunt voltage and applying the formula Actual output current Meas d shunt volt X Specified shunt current Specified shunt voltage Note any change in calibration SCPG or SCPO command will not change the sup ply output until a new program current PC command is sent ADJUST GAIN VALUE Send commands Maximum supply voltage Maximum supply current gt If itis not known read the current
11. instrument easier The latest specification SCPI adds guidelines for the command syn tax so one vendors power supply will use the same commands as anothers The Lambda interface follows all of these standards Because up to 15 instruments may be connected and independently controlled by a sin gle IEEE controller each instrument must have a unique address On the power supply the address is set by a DIP switch accessible through a slot in the back panel THE RS 232 INTERFACE The second connector on the interface board is for the RS 232 serial port It uses a 9 pin D connector Only three wires are used transmit data receive data and ground Compared to the IEEE port the RS 232 is slower and it has limited status and error re porting Also there is no instrument addressing so only one power supply can be run from each controller port The advantage of RS 232 is the cable is easy to make and every personal computer and terminal comes standard with it The RS 232 specification does not include any requirements for command syntax For this port a short form command set is available where each command has only a cou ple of characters The short form commands are easy to type into a terminal program IEEE AND RS 232 INTERACTION When the power supply is first powered up the RS 232 serial port is active If a com mand is sent over the IEEE bus the IEEE port becomes enabled and the RS 232 port will no longer function To restore the
12. similar manner but it occupies bit 1 of the Operational register The bit assignments for the Operational Registers are BIT DECIMAL BIT NUMBER VALUE SYMBOL DESCRIPTION Set high if digital Over Voltage detected Set high if digital Over Current detected 1 10 6 256 RMO Remote operation Always set high Table 4 Operational Registers 1 The Operational Condition Register Bits 0 and 1 of this register will contain zeroes unless over voltage or over current is enabled and detected To read the contents of this register use the common query Document 83 468 007 Rev B 20 STATUS OPERATION EVENT CONDITION STAT OPER COND The response message will be a binary weighted number from 0 to 259 Since bit eight is always set 256 is returned if there are no errors Over voltage bit 0 may also be read by using the query see Section 1 8 3 3 SOURCE VOLTAGE TRIPPED or VOLT TRIP After an over voltage shutdown the error may be cleared to zero by sending SOURCE VOLTAGE CLEAR or VOLT CLE Over current bit 1 may also be read by using the query see Section 1 8 4 3 SOURCE CURRENT TRIPPED or CURR TRIP After an over current shutdown the error may be cleared to zero by typing SOURCE CURRENT CLEAR or CURR CLE 1 10 6 2 The Operational Enable Register An over voltage or over current can propagate to generate a Service Request signal that will be detected by the controller performing a Serial Po
13. to asynchronously return a status value when an invalid command is received The value is the contents of the Status Byte Register This register is established by the IEEE 488 specification and it is described in detail in Sec tion 1 10 4 Study that section to follow the example below The Status Byte Register must be enabled to report errors by sending these commands over the RS 232 bus when the supply is first powered up SRE 224 Enable bits 5 6 7 in Status Byte ESE 255 Enable all bits in Std Event Status Reg STAT OPER ENAB 3 Enable OV and OC protection report After this setup any error condition will cause the power supply to send a Service Re quest Message SRM For example if an illegal command is sent the supply will re spond by returning this message over the RS 232 line SRM 96 OK The 96 equals 01100000 in binary This indicates the Status Byte Register bits 5 ESB and 6 RQS are set To see why ESB is set read the contents of the Standard Event Status Register by sending this command ESR The response from the power supply will be 32 This equals 00100000 in binary and it means bit 5 CME of the Standard Event Status Register is set This bit indicates a Command Error occurred Reading these registers will clear the errors and reset the interface to report more errors NOTE If an SRM error is NOT cleared no further errors will be reported Therefore after an error message send the comman
14. 00 LIMit Supply On Turn the Supply Output ON OUTPut ON Supply Off Turn the Supply Output OFF OUTPut OFF Current Set power supply output current SOURce Value 0 to 1000 0 CURRent AMPLitude Current Prog Set maximum current program limit Limit Value 0 to 1000 100 LIMit MEASUREMENT COMMANDS Measure Measure the voltage present at MEASure supply output VOL Tage Measures the current present at supply output Measure both voltage amp current present at none Filter Report Mode the output of supply No IEEE cmd Sets filter number for voltage measurement 1 to 250 20 Sets filter number for voltage measurement 1 to 250 20 Report the program mode SYSTem Document 83 468 007 Rev B MVC AFV AFC Command List Response is LOCAL REMOTE PROGmode or FORCED_LOCAL PROTECTION COMMANDS Set software overvoltage and overcurrent protection functions Voltage Set Protection Level SOURce Value 0 to 1000 1000 VOLTage LEVel Enable Protection ON Off Query the Protection Circuit state TRIPped Clear the tripped state CLEar Current Set Protection Level SOURce Value 0 to 1000 1000 CURRent LEVel Enable Protection ON Off STATe Query the Protection Circuit state TRIPped Clear the tripped state CLEar Report V Prog Report V Limit Report 1 Prog Report l Limit Present program voltage Present voltage limit value Present current programming val
15. BDA EMS lt max volt gt lt max curr gt S N lt supply serial gt REV lt ieee brd rev gt GO TO LOCAL This is not a command It is a function whose syntax varies with the application being executed in the controller computer When the first IEEE command is detected by the supply it goes into remote mode It s front panel voltage and current knobs cease to function A Go To Local function may be executed to temporarily return control to the front panel knobs Queries such as MEASURE VOLTAGE will put the supply back into remote mode In most applications the Go To Local may be sent with or without a trailing address If no address is used all devices on the bus will go to the local mode If an address is used only the addressed device will go to the local mode The power supply may be returned from local to remote mode by either sending a pro gramming command or by executing the Remote Enable function REMOTE ENABLE This is not a command It is a function whose syntax varies with the application being executed in the controller computer This function will cause the controller to assert the Remote Enable REN line in the IEEE cable If the power supply was in local mode it will go to remote mode when this function is executed READ STATUS BYTE REGISTER The Status Byte Register contains eight bits which are set to show that some other reg ister has recorded an event or an error This is the same register tha
16. E ADDRESS Each device on the IEEE bus must have unique address The controller is normally at address 0 and address 31 is reserved so the available addresses are from 1 to 30 See Figure 1 Before powering up the supply verify the FORCED LOCAL switch on IEEE address switch is downward for OFF Setting this switch ON will disable re mote programming over the IEEE and RS 232 busses See Figure 1 SWITCH NUMBER _ ON OFF 16 8 2 1 For A orcad PH IEEE Address Local 8 Switch Switch Switches shown default UP DOWN Address set to 4 Figure 1 IEEE Address Switch Settings Document 83 468 007 Rev B 1 5 1 5 1 GETTING STARTED WITH THE SOFTWARE A computer can use a variety of controllers programs and programming languages for the IEEE bus Here are three examples showing minimal programs to set the voltage set the current and measure the voltage from a Lambda EMI power supply EXAMPLE SESSION USING THE IBIC CONSOLE A popular console program is National Instruments Win32 Interactive Control file ibic exe As the operator types each command on the computer at the colon prompt it is immediately sent to the power supply This example works only for computers with National Instruments and compatible IEEE controller cards Win32 Interactive Control Copyright 1996 National Instruments Corporation All rights reserved help for help or to quit ibdev Controller address enter b
17. ITY Program the supply to various voltages between 10 and 100 of full output by sending the command Program Volt gt For each programmed voltage measure the actual supply output Verify the output error is less than 0 1 of the maximum voltage If the measurement is out of tolerance the supply is NOT calibrated If the voltage programming is not calibrated repeat procedure from step 3 2 1 to 3 2 4 SAVE CALIBRATION FACTORS Enter commands py 0 0 SAV 0 Document 83 468 007 Rev B 3 3 3 3 1 3 3 2 3 3 3 3 3 4 Calibrate Volt Measurement 30 CALIBRATE THE VOLTAGE MEASUREMENT Verify the load connected to the supply keeps it in voltage mode even when the voltage is set to maximum The load should not allow the current to exceed 90 of maximum current The load may be entirely disconnected from the output open load but for best results use the load typical of your application ADJUST GAIN VALUE Send commands to set supply to maximum voltage Maximum supply voltage Maximum supply current gt If itis not known read voltage measurement gain value by sending query SVRG Save response message as lt Old SVRG gt Use voltmeter to measure supply output voltage Use IEEE card to measure output voltage by sending MV and record the response message Calculate New SVRG gt Measured output voltage X Old SVRG gt Response t
18. Male Pins 5 7 Figure 4 RS 232 Cable Construction Document 83 468 007 Rev B RS 232 Configuration 24 2 2 2 2 1 RS 232 COMMAND SET Most commands listed in the IEEE section of this document will also work with the RS 232 interface Some commands are applicable only to RS 232 programming and they are listed here The power supply will acknowledge every command by returning OK followed by a linefeed character CHANGE CHARACTER ECHO The serial port has a default power up condition where any character received will be sent back to the controller This is the Echo configuration and it is one method of verifying message integrity Echo on is typically used when the operator is sending commands through a console terminal The echo will typically be turned off when an automatic computer program is the controller Echo On is set by sending the command EN Echo Off is set by sending the command EF The power supply echo may be set on or off and the controlling terminal local echo may be set on or off The supply will respond correctly with any setting but what the operator sees will change with each setting The combinations are shown in this table Controller Controller Local Echo OFF Local Echo ON Supply EOS LF Typed characters do Typed characters Echo OFF NOT appear on terminal appear on terminal Supply EOS Typed characters Typed characters Echo ON CR LF appear on terminal appear TWICE on termi
19. OPERATOR MANUAL FOR EMBEDDED IEEE 488 PROGRAMMING INTERFACE Document 83 468 007 Rev B MODEL SERIAL LAMBDA EMI 405 Essex Road Neptune NJ 07753 Tel 732 922 9300 732 922 9334 Web www lambda emi com Table of Contents 1 THE DIGITAL PROGRAMMING OPTION eere 1 1 4 OVERVIEW IEEE AND RS 232 PORTS esee 1 1 22 SCOPE OF MANUAL 0 14012111 2 1 3 USING DIGITAL PROGRAMMING 2 1 3 1 THE IEEE 488 2 2 1 3 2 THE RS 232 0 8 812 2 1 3 3 IEEE AND RS 232 INTERACTION eee 2 1 4 CONFIGURING THE IEEE INTERFACE reet 3 1 4 10 CONFIGURING THE IEEE 3 142 CONFIGURING THE IEEE INTERFACE 3 1 5 GETTING STARTED WITH THE SOFTWARE seen 4 1 5 1 EXAMPLE SESSION USING THE IBIC 4 1 5 2 EXAMPLE PROGRAM WRITTEN IN VISUAL BASIC 4 1 5 3 EXAMPLE PROGRAM WRITTEN IN 5 1 6 PROGRAMMING VOLTAGE AND 6 1 6 1 PROGRAM OUTPUT VOLTAGE eee 6 1 6 2 PROGRAM OUTPUT CURRENT 6 1 6 3 DISABLE THE SUPPLY O
20. PTRansition NTRansition CLS SRE lt value gt SRE ESE lt value gt ESE ESR 10 OPC OPC RCL 0 Reset Save Restores its power up state except that the state of IEEE 488 interface is unchanged Saves current SCPI configuration in flash So it becomes the new power on setting Read Status Byte Self Test Query Causes the controller to respond with last self test status Wait to Continue CALIBRATE Calibrate Calibrate Lock Set Identity Set Date Establishes programming gain Slope range Offset range Slope range Offset range Establishes measurement gain Gain range Offset range Gain range Offset range Prevents unauthorized changes to other calibration values Value 0 or 1 OFF or ON Allows entry of text string up to 72 characters four comma fields Ex Mfgr Model Serial Number Revision Allows input of calibration date in mm dd yyyy format Document 83 468 007 Rev B Command List 38 RST SAV 0 STB TST WAIt CALibrate SOURce VOLTage SLOPe OFFset CURRent SLOPe OFFset CALibrate MEASure VOLTage GAJN OFFset CURRent GAIN OFFset CALibrate LOCK CALibrate CALibrate DATe RS SVPG SVPO SCPG SCPO SVRG SVRO SCRG SCRO SLOCK SIDN SDAT Notes Document 83 468 007 Rev B 39
21. Private Declare Function GetTickCount Lib kernel32 As Long Private Sub cmdStart Click start program here after Start button clicked open IEEE port get User Device Description LambdaUD assume power supply address is set to 4 on DIP switch Call ibdev 0 4 O T3s 1 10 intLambdaUD Call ibwrt LambdaUD volt 100 program output to 100 volts Call ibwrt LambdaUD curr 2 program output to 2 amps Wait 500 wait 0 5 sec for output to settle Call ibwrt LambdaUD meas volt ask What is output voltage Call ibrd LambdaUD strMeasVolt read back output voltage txtOutVolt Text strMeasVolt display output voltage on window End Sub Private Sub Wait mSecWait As Long subroutine to wait mSecWait milliseconds Dim StartTime As Long StartTime GetTickCount Do Loop While GetTickCount StartTime mSecWait End Sub 1 5 3 EXAMPLE PROGRAM WRITTEN IN LABVIEW The National Instruments LabVIEW programming language is a popular language which is optimized for instrument control and data analysis It is a graphical language where functions are shown as icons with connection points and data flows along drawn lines Here is a simple program which sends commands to a Lambda EMI power supply to set the voltage set the current and measure the voltage The program s window only cona tains two items a numeric control for the supply IEEE address and a text indicator to show the
22. UTPUT 6 1 6 4 ENABLE THE SUPPLY OUTPUT eee 7 1 6 5 READ PROGRAMMING MODE eee 7 1 7 MEASURING VOLTAGE AND 8 TET MEASURE VOLTAGE iei epe E ei pates 8 1 7 2 MEASURE CURREN T aiitra eene entren 8 1 7 3 SET MEASUREMENT FILTERING 8 1 8 LIMITS AND PROTECTIONS esses nennen 9 148 1 MOETAGE LIMMIT iuit wi 9 1 8 2 SET CURRENT ae oett 9 1 8 3 PROTECTION seen 9 1 8 44 OVER CURRENT PROTECTION eene 10 1 9 COMMON 5 4 000011111 12 1 9 1 READ DEVICE IDENTITY 12 49 2 GOTO LOCALS e 12 1 9 3 REMOTE ENABLE lt lt eren ce tree dee edere ee ra 12 1 9 4 READ STATUS BYTE 12 1 9 5 RESET THE POWER 13 1 96 CHANGING THE POWER UP 8 2 22 2 424 13 1 10 USING ERROR AND STATUS REGISTERS 13 1 10 1 OVERVIEW REGISTER FAN OUT eee 14 1 10 2 GLOSSARY OF REGISTER 5
23. bled so only selected events will cause a service request The syntax for writing to the Standard Event Enable Register is ESE lt nn gt where lt nn gt is a number between zero and 255 A space is required before the number The power up default is all zeroes in the enable register This means no status or errors will be sent to the Status Byte Register However even if no bits are enabled the con tents of the Standard Event Status Register may always be read with the ESR query The contents of the Standard Event Enable Register may be read by sending ESE The response will be a bit weighted number whose bits correspond to Table 3 THE OPERATIONAL REGISTERS The Operational Registers are three 16 bit registers whose bits are not defined by the IEEE specification but are specific to the IEEE device In the power supply bits 0 and 1 are set when an over voltage or over current event has occurred Digital over voltage protection is enabled by sending the SOUR VOLT STAT ON com mand see Section 1 8 3 If an over voltage occurs bit zero of the Operational Condi tion Register will be set high If bit O of the Enable register is set high the over voltage will set bit O of the Event register This in turn sets bit 3 of the Standard Event Register to illuminate the red ERROR LED It also sets bit 3 in the Status Byte Register so the over voltage error becomes detectable by a Serial Poll sent by the controller Digital over current works in a
24. d CLS Document 83 468 007 Rev B Calibrate Volt Programming 28 3 ADJUST THE IEEE CALIBRATION 3 1 3 2 3 2 1 3 2 2 INTRODUCTION It may be necessary to adjust the calibration of the digital programming and measure ment circuit commands The following instructions explain how to select new calibration factors and save them into the interface nonvolatile memory NOTE These instructions are only good for slight adjustments to the digital interface The power supply must be in good operating condition and it must have been previously calibrated by the factory These instructions are NOT sufficient to setup a new IEEE interface board into a power supply The following commands may be sent using a terminal connected to the IEEE 488 or the RS 232 port Only the short forms of the commands are shown Commands are shown inside double quotes Do not type the quotes CALIBRATE THE VOLTAGE PROGRAMMING Verify the load connected to the supply keeps it in voltage mode even when the voltage is set to maximum The load should not allow the current to exceed 90 of maximum current The load may be entirely disconnected from the output open load but for best results use the load typical of your application Note any change in calibration SVPG or SVPO command will not change the supply output until a new program voltage command is sent ADJUST GAIN VALUE Send commands Maxim
25. dard Event Status Reg ister will be set To read what current limit has been set send query CURR LIM and read the response message The short form for set current limit is SCL lt nn nn gt OVER VOLTAGE PROTECTION Lambda supplies feature two types of over voltage protection that shuts down the output if the output exceeds some settable voltage level The analog method uses the Over Voltage Adjustment potentiometer on the front panel The digital method uses the IEEE board to constantly sample the supply output voltage The analog pot setting always takes priority over any digital programmed level Therefore for digital over voltage pro tection it is recommended the potentiometer be turned clockwise to maximum Document 83 468 007 Rev B Limit Output 10 Using IEEE protection the time between an over voltage occurring and the supply shut ting down is typically 20 milliseconds This is the time for two successive readings to ex ceed the limit The analog protection responds much faster There is no analog over current protection IEEE over voltage protection is implemented with four commands 1 8 3 1 Set the over voltage threshold SOURCE VOLTAGE LEVEL lt nn nn gt or VOLT LEV lt nn nn gt where lt nn nn gt is a number between zero and the maximum supply output voltage The decimal is optional The voltage may be more or less than the limit set by the SOURCE VOLTAGE LIMIT command described in the previous paragrap
26. e 1 The short form for this command is MH Document 83 468 007 Rev B Measure Output 8 1 7 1 7 1 1 7 2 1 7 3 MEASURING VOLTAGE AND CURRENT MEASURE VOLTAGE The output voltage can be measured by sending the command MEASURE VOLTAGE or MEAS VOLT When the controller does the next IEEE Read the supply will send the measured volt age to it The measurement is always given to six decimal places even if the measure ment is not so accurate See the Specifications Section in the power supply User Manual for actual measurement accuracy If the back panel analog connector is wired for Re mote Voltage Sensing the measured value will be the voltage at the sense lines not the voltage at the supply output The short form for measure voltage is MV MEASURE CURRENT The output current can be measured by sending the SCPI command MEASURE CURRENT or MEAS CURR When the controller does the next IEEE Read the supply will return the amperes of cur rent being produced The measurement is always given to six decimal places even if the measurement is not so accurate See the Specifications Section in the power supply User Manual for actual measurement accuracy The short form for measure current is MC SET MEASUREMENT FILTERING The output voltage or current may be queried with MEAS VOLT or MEAS CURR Be cause of noise the measurements may have unacceptable random variations There fore a routine is implemented
27. en 10 and 100 of full output by sending the command PC Program Current gt For each programmed current measure the actual supply output Send MC query and record the response message Verify the difference between the MC response and the actual output current is less than 0 1 of the full output current If the error at any level is greater than 0 1 of full output then the current measure ment on the IEEE card is NOT calibrated If the IEEE measurement is NOT calibrated repeat procedure from Step 3 5 1 to Step 3 5 4 3 5 6 SAVE CALIBRATION FACTORS Enter commands 0 is zero not letter py 0 PC 0 SAV 0 Document 83 468 007 Rev B Command List 4 SUMARY TABLE OF COMMANDS This is summary of the IEEE and RS 232 command set In most cases the long form SCPI and short form commands are both valid for either IEEE or RS 232 programming 35 When a command includes a value that value can usually be read back by appending a question mark to make the command into a query In the command format small letters are optional and words in square brackets are op tional See example in Section 1 6 1 Short Form PV SVL SN SF PC SCL MV MC Command Name Description Command Format SCPI PROGRAMMING COMMANDS Voltage Set power supply output voltage SOURce Value is 0 to 1000 VOLTage AMPLitude Voltage Prog Set maximum voltage program limit Limit Value is 0 to 10
28. function to the RS 232 port the power supply must be cycled off and on Document 83 468 007 Rev B Beginni amp Gg Siaguwarg 3 1 4 CONFIGURING THE IEEE INTERFACE 1 4 4 CONFIGURING THE IEEE CONTROLLER A typical IEEE controller is a personal computer with a IEEE interface card Each card vendor supplies its own configuration instructions and interface software Each time the software is executed the controller must be configured as follows Controller Address 0 This is factory default for all controllers EOI Flag TRUE The End or Identify is a control line in the IEEE cable that is asserted when the last character of a message string is sent It is required for Lambda EMI supplies EOS FALSE The End of String is used in some instruments to say character such as a linefeed marks the last character of a message The Lambda EMI supply does not require an end of string character 1 4 2 CONFIGURING THE IEEE INTERFACE The power supply is connected to the controller using a standard IEEE 488 cable Stan dard connecting requirements are as follows Verify the power supply is switched OFF before connecting any cables to it maximum of 15 devices may be connected to any one IEEE bus Maximum cable length between any two devices should be six feet Total cable length should be less than 65 feet Before powering up the supply set the IEEE address on its back panel switch It is labeled IEE
29. haracter set is eight bits If a bit is taken for parity checking only seven bits are allowed for each character The number of data bits is set with the command SYSTEM COMM SERIAL BITS 8 or 7 gt SYST COMM SER BITS lt 8 or 7 This command will not take affect until a SYST COMM UP ora SAV O is sent Document 83 468 007 Rev B 2 2 5 2 2 6 RS 232 Configuration 26 CHANGE THE PARITY BITS Parity is error checking done by the interface hardware If parity is enabled the data length may only be seven bits Typically parity checking is not needed so the default is None The parity is set with the command SYSTEM COMM SERIAL PARITY lt Ptype gt or SYST COMM SER PAR lt Ptype gt where lt Ptype gt is or ODD or EVEN This command will not take affect until SYST COMM UP ora SAV 0 is sent CHANGE THE STOP BITS 1 or 2 stop bits may follow each character sent over the RS 232 bus The default is 1 The number of stop bits are set with the SYSTEM COMM SERIAL SBITS lt 1 or 2 gt SYST COMM SER SBITS lt 1 or 2 gt This command will not take affect until a SYST COMM UP ora SAV 0 is sent Document 83 468 007 Rev B 2 3 RS 232 Error Registers 27 ERROR REGISTERS AND RS 232 In the power up default condition the power supply acknowledges all commands by re turning OK The OK is returned even after an invalid command is sent The RS 232 in the supply may be set
30. hs The set voltage level may be read by sending the query VOLT LEV and reading the re sponse number The short form for set voltage protection level is SVPL lt nn nn gt 1 8 3 2 Enable the protection SOURCE VOLTAGE STATE ON or VOLT STAT The protection can be disabled by specifying OFF instead of ON The state of the protection may read by sending the query VOLT STAT and reading the response A 1 one means the protection is enabled The short form for set voltage protection state 15 SVPS ON or OFF 1 8 3 3 Query for over voltage shutdown SOURCE VOLTAGE TRIPPED or VOLT TRIP Read the response number The normal response is 0 zero If a 1 one is returned it means an over voltage has occurred and the output is shut down The response number is actually the value of the Operational Condition Register Bit O Because an over voltage can set bits in four IEEE registers it is recommended that a CLS be sent to clear them after an over voltage occurs See the Section 0 on Status and Error Register Programming for more details The short form for set voltage protection tripped is SVPT 1 8 3 4 Reset after shutdown 1 8 4 SOURCE VOLTAGE CLEAR or VOLT CLE After an over voltage shut down has occurred this command must be sent to clear the error status before any new voltage commands will be accepted If and over voltage is not cleared and a new voltage command is sent the c
31. iver It is sketched in Figure 3 1 10 2 GLOSSARY OF REGISTER TERMS SERVICE REQUEST When an instrument on the IEEE bus asserts the SRQ line in the cable it tells the controller that it has completed its task or that an error has occurred SERIAL POLL An IEEE function which reads back the data in an instrument s Status Byte Register The controller should perform this function after every command to verify the command was successful REGISTER QUERIES Read the contents of registers The contents are re turned as a binary weighted decimal number CONDITIONAL REGISTERS These contain bits that are set when an event or error occurs The bits are only cleared when the event or error is cleared The contents may be read but not changed ENABLE REGISTERS The various Enable Registers can be set to allow the status and errors to be detectable by a Serial Poll EVENT REGISTERS These contain bits that are set when an event or error occurs The bits are cleared when the contents of the register are queried Document 83 468 007 Rev B 15 Error Registers jddns IIN3 y jo ou 10 seu 5141 ejduiexe z ggp 3aal 94 jjoexo JOU soop 5141 5 433 JON T yndjno mus 111111 uu SSH sorsi6oy y y S IS IS IN S c NENNEN
32. ll The propagation is enabled by sending the command STATUS OPERATION EVENT ENABLE nn STAT OPER ENAB nn where nn is a number between 0 and 3 A space is required before the number Al though this is a 16 bit register the most significant bit 15 is not used and trying to set it high will cause a Command Error The power up default is all zeroes in the enable register This means no protection er rors will be sent to the Status Byte Register However even if no bits are enabled the contents of the Operational Event Register may always be read with the STAT OPER COND query The contents of the Operational Enable Register may be queried by sending STATUS OPERATION EVENT ENABLE or STAT OPER ENAB The response will be a bit weighted number whose bits correspond to Table 4 1 10 6 3 The Operational Event Register If over voltage and over current errors are reported by the Operational Condition Regis ter and they are enabled by the Operational Enable Register the error will be loaded into the Operational Event Register The Event register differs from the Condition regis ter because the Event register is cleared to all zeroes when its contents are read whereas a bit set in the conditional register remains set until the condition is removed The contents of the Operational Event register is read by the command STATUS OPERATION EVENT or STAT OPER EVEN Document 83 468 007 Rev B Error Registers 21 The respo
33. measured voltage Pwr Supply Address on DIP Switch Eus PIB Initialization Controller t E EJ EJ B Address f g Simple Error Handler vil 5 Open IEEE Program Program Wait Ask Read Display Port Output to Output to 0 5 Voltage Voltage Voltage 25 Volts 40 Amps Document 83 468 007 Rev B BedinognagrS 6 1 6 1 6 1 1 6 2 1 6 3 PROGRAMMING VOLTAGE AND CURRENT PROGRAM OUTPUT VOLTAGE The output voltage can be programmed by sending the command SOURCE VOLTAGE AMPLITUDE lt nn nn gt where lt nn nn gt is any valid voltage with or without decimal places There must be a space before the number Per the Summary Table in Section 4 the command can be abbreviated in any of the fol lowing ways SOUR VOLT AMPL lt nn nn gt SOUR VOLT lt nn nn gt VOLT AMPL lt nn nn gt VOLT lt nn nn gt The power supply output will not reach the programmed voltage until a Program Current command is also sent To get the sharpest transition from zero to programmed output disable the output Section 1 6 3 program voltage and current then enable the output If the voltage is more than the supply output or less than zero the command will be ig nored and the Command Error bit of the Standard Event Status Register will be set If the voltage is higher than the limit set by the SOURCE VOLTAGE LIMIT value the command will be igno
34. nal EOS End Of String Terminator Table 6 RS 232 Echo Settings Document 83 468 007 Rev B 2 2 2 2 2 3 2 2 4 5 232 Confiquration 25 GO TO LOCAL COMMAND The power supply may be commanded into LOCAL mode where the front panel knobs will set the output voltage and current The command for Set Local is SL After receiving the SL command the supply will remain in LOCAL mode until the next command or query is received The SR command may also be used to set remote WARNING When a Go To Local command is sent the supply output will jump to whatever is set on the front panel knobs Therefore it is recommended the front panel Voltage and Current knobs be turned counter clockwise to ZERO before REMOTE programming CHANGE THE BAUD RATE The serial port may be set to any speed specified by the RS 232 specification The speed called the BAUD rate is in bits per second The actual message rate includes the Bits per Byte the Start Bit the Stop Bits and the Parity Bit The default BAUD rate is 9600 The BAUD rate will be changed by sending command SYSTEM COMM SERIAL BAUD lt nnn gt or SYST COMM SER BAUD lt nnn gt where nnn is one of these standard values 110 1200 4800 19200 300 2400 9600 38400 This command will not take affect until a SYST COMM UP ora SAV 0 is sent CHANGE THE DATA BITS Each character sent over the RS 232 bus may use 7 or 8 data bits The default ASCII c
35. ng the command Program Volt gt For each programmed voltage measure the actual supply output Verify the output error is less than 0 1 of the maximum voltage If the measurement is out of tolerance the supply is NOT calibrated If the voltage programming is not calibrated repeat procedure Steps 3 4 1 to 3 4 4 SAVE CALIBRATION FACTORS Enter commands 0 is zero not letter py 0 0 SAV 0 CALIBRATE THE CURRENT MEASUREMENT Verify the load connected to the supply keeps it in current mode even when the current is set to maximum The load should not allow the voltage to exceed 90 of maximum Document 83 468 007 Rev B Calibrate Current Measurement 33 voltage A cable may be connected across the output terminals shorted load but for best results use the load typical of your application Throughout this section references are made to lt Actual output current gt Since we cannot measure current directly the lt Actual output current gt is found by connecting a series shunt resister measuring the shunt voltage and applying the formula Actual output current _ lt Meas d shunt volt X Specified shunt current Specified shunt voltage 3 5 1 ADJUST GAIN VALUE Send commands to set supply to maximum current Maximum supply voltage Maximum supply current gt If itis not known read existing current measurement gain by sending query SCRG
36. nse message will be a binary weighted number from 0 to 3 Zero is returned if there are no protection errors The contents of the Operational Event Register will be cleared to zeroes after the STAT OPER EVEN is received 1 10 7 THE QUESTIONABLE REGISTERS These are a set of registers required by the IEEE 488 2 specification They have a simi lar structure and command set as the Conditional Registers described in the previous section Since the Questionable Register is not used by Lambda supplies it is not de scribed here Document 83 468 007 Rev B RS 232 Configuration 22 2 THE RS 232 INTERFACE 2 1 The optional IEEE interface board has 9 pin connector for the RS 232 serial port It uses only three wires to transmit data receive data and connect ground The port is Full Duplex where the power supply and the controller may both transmit messages at the same time Compared to the IEEE port the RS 232 is slower and it has limited status and error reporting Also there is no instrument addressing in the RS 232 port so only one power supply can be run from each port in the controller The advantages of RS 232 is the cable is easy to make and every personal computer comes standard with this port CONFIGURING THE RS 232 INTERFACE THE RS 232 CABLE The power supply RS 232 port is configured as a DCE device It has a 9 pin female connector A modem cable not null modem is used to connect it to a personal com pute
37. o MV Send command SVRG New SVRG gt Repeat this step until the response from the MV query is within 0 05 of the meas ured output voltage ADJUST OFFSET VALUE Send command to set supply to 1096 of its maximum voltage Tenth of maximum supply voltage gt Maximum supply current gt If itis not known read existing voltage offset value by sending query SVRO Save the response message as lt Old SVRO gt Use IEEE card to measure output voltage by sending MV Record the response message Measure the supply output voltage If the response to the MV query is higher than this measurement you have to choose a lower value for SVRO If the response message is lower choose a higher SVRO Picking the correct SVRO is a trial and error process It is typically 0 001 and it must be between 0 1 and 0 1 Send new calibration factor by sending command SVRO lt New SVRO gt Repeat this step until the value returned from the MV query is within 0 05 of the measured output voltage Document 83 468 007 Rev B Calibrate Current Programming 31 3 3 5 3 3 6 3 4 3 4 1 3 4 2 VERIFY VOLTAGE MEASUREMENT LINEARITY Program the supply to various voltages between 10 and 100 of full output by sending the command Program Volt gt For each programmed voltage measure the actual supply output Send MV query and record the response message Verify the
38. oard index O0 Supply Address on DIP Switch enter primary address 4 der enter secondary address 0 enter timeout 13 enter EOI on last byte flag 1 nter end of string mode byte 10 Program supply to ud0 ibwrt sour volt 100 49 o Vols 0100 cmpl count 12 Program supply to ud0 ibwrt sour curr 5 ducem 0100 cmpl counts 11 Query What is ibwrt meas volt pe n 0100 1 count 10 se qu ud0 ibrd 50 2100 end cmpl Supply reported output voltage count 11 31 30 30 2 30 38 33 31 100 0831 30 31 0 Q bos 1 5 2 EXAMPLE PROGRAM WRITTEN IN VISUAL BASIC Microsoft s Visual Basic is a windows programming language that may be used to create virtual instruments and automation programs Here is a simple program which sends commands to a Lambda EMI power supply to set the voltage set the current and meas ure the voltage The program s window only conatains two items a Start button and a text box to show the measured voltage The syntax of the CALLed functions are correct only for National Instruments and compatible IEEE controllers Don t forget to add the forms Ni global bas and Vbib 32 bas to you project Document 83 468 007 Rev B Beginning Software 5 Example Program Written in Visual Basic Option Explicit Dim LambdaUD As Integer supply device descriptor Dim strMeasVolt As String 50 buffer for reading input message
39. ommand will be ignored and the Command Error bit in the Standard Event Status Register will be set The short form for set voltage protection clear is SVPC OVER CURRENT PROTECTION The IEEE Interface board constantly measures the power supply output current and the board can be set to shut down the supply if the output current exceeds a settable level The time between an over current occurring and the supply shutting down is typically 20 milliseconds Document 83 468 007 Rev B Limit Output 11 Over current protection is implemented with the following four commands 1 8 4 1 Set the over current threshold SOURCE CURRENT LEVEL lt nn nn gt or CURR LEV lt nn nn gt where lt nn nn gt is a number between zero and the maximum supply output current The decimal is optional The current may be more or less than the limit set by the SOURCE CURRENT LIMIT command described in the previous paragraphs The set current level may be read by sending the query CURR LEV and reading the re sponse number The short form for set current protection level is SCPL lt nn nn gt 1 8 4 2 Enable the protection SOURCE CURRENT STATE ON or CURR STAT ON The protection can be disabled by specifying OFF instead of ON The state of the protection may read by sending the query CURR STAT and reading the response A 1 one means the protection is enabled The short form for set current protection state is SCPS ON or OFF 1 8 4
40. programming gain by sending query SCPG Save response message as Old SCPG gt Measure supply output current and calculate New SCPG gt Old SCPG X Maximum supply current Actual output current Document 83 468 007 Rev B Calibrate Current 32 3 4 3 3 4 4 3 4 5 3 4 6 3 5 Send commands SCPG lt New SCPG gt PC lt Maximum supply current gt Repeat this step until lt Actual output current gt is within 0 05 of the lt Maximum supply current gt ADJUST OFFSET VALUE Send commands to set supply to 10 of its maximum current PV Maximum supply voltage gt PC lt Tenth of maximum supply current gt If not known read existing current programming offset by sending query SCPO Save response message as lt Old SCPO gt Measure supply output current If it is higher than the target 10 of its maximum cur rent then choose a lower value for the next SCPO factor If the output is too low choose a higher SCPO Picking the correct SCPO is a trial and error process It is typi cally 0 001 and it must be between 0 03 and 0 5 Send commands SCPO lt New SCPO gt PC lt Tenth of maximum supply current gt Repeat steps 3 and 4 until actual output current is within 0 05 of the expected 10 of full output VERIFY CURRENT PROGRAMMING LINEARITY Program the supply to various voltages between 10 and 100 of full output by sendi
41. query ESR The response message will be a binary weighted number from 0 to 255 Zero is returned if there are no errors or events The contents of the Standard Event Status Register will be cleared to zeroes after the ESR Query is received The bit assignments for this register are BIT DECIMAL BIT NUMBER VALUE SYMBOL DESCRIPTION ee OPC Operation complete Not used 2 ww 2 7 2 4 QUE Query Error Set if illegal string ending with a question mark is received 3 DDE Device Dependant Error Set if over voltage or over current is enabled and detected 5 32 CME Command Error Typically set if unrecognized command string was received User Request Set at power up if interface board has not been calibrated by manufacturer 4 16 EXE Execution Error Typically set if programming command is outside of legal range PON Power On Set when power is switched on Table3 The Standard Event Status Register 1 10 5 1 The Standard Event Enable Register If the bits in the Standard Event Status Register are enabled an error will propagate to the Status Byte Register see Section 1 10 4 If bit 5 in the Status Byte is enabled with the SRE 32 command this error will cause the Service Request to be asserted By Document 83 468 007 Rev B Error Registers 19 1 10 6 writing a binary weighted value to the Standard Event Enable Register the bits in the Standard Event Status Register may be individually ena
42. r The cable may be up to 50 feet long It has three wires transmit data receive data and ground The cable must be twisted and or shielded To reduce ground loops only one end of the shield should be connected to chassis earth ground See Figure 4 for details of cable construction DEFAULT RS 232 CONFIGURATION The controller and the power supply must configured to the same signal timing and mes sage control The factory default settings are shown in Table 5 below On the power supply end the default settings may be changed by using the commands in the following section Parameter Default Value Notes Baud Rate 9600 Bits per Second Data Bits 8 ASCII Characters Parity None Stop Bits 1 Flow Control None No Handshaking Char Echo On See Echo command EOS LF ASCII 10 End of String Table 5 Default RS 232 Configuration Remember to verify the Forced Local switch is set down to OFF The switch is rocker number 1 on the IEEE Address selector shown in Figure 1 Document 83 468 007 Rev B RS 232 Configuration 23 Data Flow Data Flow Pin to Pin DCE 2 2 DTE DB 9 Connector 3 3 DB 9 Connector Female Sockets 5 65 Male Pins Power to 25 PinPC 222 Supply NOTE 25 to 9 Pin adapter is used it may reverse ZI i pins 2 and 3 In this case pins 2 and 3 in cable are straight O Shield DCE m to DTE DB 9 Connector _ DB 25 Connector Female Sockets 3 2
43. red and the Execution Error bit of the Standard Event Status Reg ister will be set To read what voltage the supply was programmed to regardless of the actual voltage send query SOUR VOLT AMPL and read the response message The short form of program voltage is PV nn nn PROGRAM OUTPUT CURRENT The output current is programmed by sending the command SOURCE CURRENT AMPLITUDE lt nn nn gt or CURR lt nn nn gt where lt nn nn gt is any valid current with or without decimal places There must be a space before the number The power supply output will not reach the programmed current until a program voltage command is also sent To get the sharpest transition from zero to programmed output disable the output Section 1 6 3 program voltage and current then enable the output If the lt nn nn gt is more than the supply output or less than zero the command will be ig nored and the Command Error bit of the Standard Event Status Register will be set If the current is higher than the limit set by the SOURCE CURRENT LIMIT value the command will be ignored and the Execution Error bit of the Standard Event Status Reg ister will be set To read what current the supply was programmed to regardless of the actual output cur rent send query SOUR CURR AMPL and read the response message The short form of program current is PC lt nn nn gt DISABLE THE SUPPLY OUTPUT Document 83 468 007 Rev B 1 6 4 1 6 5
44. rent knobs be turned counter clockwise to ZERO before REMOTE programming 1 THE DIGITAL PROGRAMMING OPTION 1 1 OVERVIEW IEEE AND RS 232 PORTS Most power supplies come standard with the Local and Analog Remote programming modes which use the front panel knobs or the back panel 25 pin D connector A third programming mode Digital Remote is available as an option This option adds an em bedded interface board with two extra connectors to the back of the supply The connectors allow cables to be run from the supply to a remotely located operator terminal or to a computer running an automation program A terminal allows the operator to type commands to the power supply which take affect as soon as they are typed An automation program will allow several power supplies to be daisy chained together It also allows other instruments including relay switchers and measurement devices to be synchronized with the power supplies in complex power systems When the supply is running in the digital programming mode the front panel knobs are disabled but all the front panel indicators still show the status of the supply The power supply output levels and operating states may be monitored through the computer port Commands that are standard with digital programming include e Program Voltage e Program Current e Measure Voltage e Measure Current e Set Maximum Voltage e Set Maximum Current e Over Voltage Shutdown e Over Current Shu
45. so the board makes measurements every 16 milliseconds and keeps a running average of the output The number of samples in the running average may be adjusted A higher number will smooth constant output readings but it will slow down the reported response to actual changes in output The voltage measurement averaging is set by the command AFV nnn Where nnn is a number between 1 and 250 The default is 20 The current measurement averaging is set by the command AFC nnn Where nnn is a number between 1 and 250 The default is 20 Changing the averaging value will not slow down the bus speed or slow down the re sponse time to an over voltage and over current shutdown Any changes or AFC may be made the power up default by sending the SAV 0 command Document 83 468 007 Rev B Limit Output 9 1 8 1 8 1 1 8 2 1 8 3 LIMITS AND PROTECTIONS SET VOLTAGE LIMIT The maximum voltage that may be programmed to the power supply is set by the follow ing command It does not monitor the actual output voltage It only inspects the numeric value a voltage programming command SOURCE VOLTAGE LIMIT lt nn nn gt or VOLT LIM nn nn where lt nn nn gt is a number between zero and the maximum supply output voltage The decimal is optional A space is required before the number By default the voltage limit equals the power supply maximum voltage A new voltage limit will remain in effect until the supply po
46. t is read by the Se rial Poll function See Section 1 10 4 Serial Poll for details STB The response to this query will be a binary weighted number from 0 to 255 See descrip tion of Status Byte in Table 2 for the meaning of each of the bit positions Using the STB query is not recommended because it puts its response in the Output Queue and it sets the Message Available bit in the Status Register If a previous query had already done these things the IEEE bus will lock up until the controller generates a Timeout Error Document 83 468 007 Rev B 13 1 9 5 RESET THE POWER SUPPLY The supply will be reset to Local mode and all registers cleared to the power up state by sending RST 1 9 6 CHANGING THE POWER UP DEFAULTS Many calibration scaling identity and operational variables are stored in Electrically Erasable Programmable Read Only Memory EEPROM These values are the power up default settings To change one or more default settings enter the one or more commands with new set tings and then enter this command SAV 0 This will write any changed settings to the IEEE board EEPROM WARNING When a power supply is set to REMOTE mode its output will jump to the last voltage and current programmed before the last SAV 0 Therefore it is recommended the commands VOLT 0 and CURR 0 be sent immediately before SAV 0 is sent The following commands will load values that
47. tdown e Error and Status Messages e Computerized Calibration EEE 488 2 Compliant e SCPI Compliant Document 83 468 007 Rev B Introduction 2 1 2 1 3 1 3 1 1 3 2 1 3 3 SCOPE OF MANUAL This manual contains the information needed to setup and operate the embedded digital interface used in the Lambda EMI power supplies including the EMS and ESS models The interface is contained on one circuit card It may be optionally installed by Lambda facilities at the time of purchase This manual does NOT include specifications for digital accuracy and response rate These values are only valid for the power supply in which the interface is installed so the specifications are given in the User Manual for the power supply USING DIGITAL PROGRAMMING THE IEEE 488 2 INTERFACE The IEEE 488 digital programming interface also called the GPIB interface is a popular way to connect instruments to a computer It uses a specialized 24 pin cable with con nectors that allow cables to be stacked together There are eight data wires eight con trol wires and eight ground wires If the system runs from a personal computer there are numerous vendors of IEEE controller cards and software The IEEE 488 standard has gone through several upgrades The IEEE 488 1 focused on the handshaking of the eight control lines The IEEE 488 2 added status registers in side each instrument and it added common commands to make programming groups of
48. ue Present current limit value RS 232 SPECIFIC COMMANDS Set Local Set Remote Set Echo On Set Echo Off Address Set Program Mode to Local Set programming to Remote Mode Allows Controller to echo back commands received plus OK Controller only returns OK Reads address switch setting Document 83 468 007 Rev B 36 MH SVPL SVPS SVPT SVPC SCPL SCPS SCPT SCPC MVP MVL MCP MCL SL SR EN CNTL E EF CNTL F EXTADR Following commands take affect after a SAV 0 RCL 0 or an UPdate Set BAUD Sets baud rate 50 to 38 400 9600 Set Bits Set of Data Bits 7 or 8 8 Set Stop Bits Set of Stop Bits 1 or2 1 Set Parity Sets parity none Odd or Even none Update Updates UART with new settings Command List 37 SYSTem COMM SERial BAUD BITS 5 5 PARity UPdate STATUS COMMANDS SCPI required Status Register Commands Operation Operational Registers Questionable Questionable Registers IEEE 488 2 COMMANDS Clear Status Service Request Enable 0 to 255 Service Request Enable Query Event Status Enable 0 to 255 Event Status Enable Query Event Status Register Query Identification Query Operation Complete Command Operation Complete Query Recall Restores the power on setting Document 83 468 007 Rev B STATus OPERational EVENt CONDiition ENABIe PTRansition i NTRansition STATus QUEStionable EVENt CONDiition ENABIe
49. um supply voltage Maximum supply current gt If itis not known read voltage programming gain value by sending query SVPG Save response message as lt Old SVPG gt Measure supplies output voltage and calculate New SVPG gt Old SVPG X Maximum supply voltage Voltage measured at output Send commands SVPG New SVPG gt Document 83 468 007 Rev B Calibrate Volt Programming 29 3 2 3 3 2 4 3 2 5 3 2 6 PV Maximum supply voltage gt Repeat this step until lt Voltage measured at output gt is within 0 05 of the lt Maximum supply voltage gt ADJUST OFFSET VALUE Send commands to set supply to 10 of its maximum voltage Tenth of maximum supply voltage gt PC lt Maximum supply current gt If it is not known read voltage programming gain value by sending query SVPO Save response message as lt Old SVPO gt Measure supply output voltage If it is higher than the target 10 of its maximum volt age then choose a lower value for the next SVPO factor If the output is too low choose a higher SVPO Picking the correct SVPO is a trial and error process It is typi cally 0 001 and it must be between 0 3 and 0 5 Send commands SVPO lt New SVPO gt PV lt Maximum supply voltage gt Repeat this step until the measured output voltage is within 0 05 of the expected 10 of full output VERIFY VOLTAGE PROGRAMMING LINEAR
50. wer is switched off A new voltage limit can be made to be the power up default by following VOLT LIM with the 0 command See Section 1 9 6 for a description of the SAV 0 command If a command is sent to set the supply to a voltage higher than the voltage limit the command will be ignored and the Execution Error bit of the Standard Event Status Reg ister will be set To read what voltage limit has been set send query VOLT LIM and read the response message The short form for set voltage limit is SVL lt nn nn gt SET CURRENT LIMIT The maximum current that may be programmed to the power supply is set by the follow ing command It does not monitor the actual output current It only inspects the numeric value in a current programming command SOURCE CURRENT LIMIT lt nn nn gt or CURR LIM lt nn nn gt where lt nn nn gt is a number between zero and the maximum supply output current in amperes The decimal is optional A space is required before the number By default the current limit equals the power supply maximum current A new current limit will remain in effect until the supply power is switched off A new current limit can be made to be the power up default by following CURR LIM with the SAV 0 command See Section 1 9 6 for a description of the SAV 0 command If a command is sent which sets the supply to a current higher than the current limit the command will be ignored and the Execution Error bit of the Stan
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