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7900 Users Guide 711801.vp

1. Display Y gt Temperature ke Program Menu SET se Ne Number of Setpoints H EXIT Reset Cutout i SET i Cutout Active y EII IE y A Select Setpoint Select Setpoint EXIT Select Setpoint 3l DT SoakTime SECONDARY FUNCTIONS EXIT Adjust Setpoint I U gt SET EXT m Y Program Function Mode EXIT Adjust Vernier rt EXIT Display Power EXT SET Y Y Program Control EXIT Set Scale C F EXIT Set Proportional Band et Scale P 1 SET Y EXIT Scan On Off EXIT Set Cutout Temp I SET y EXIT Scan Rate Le EXIT Configuration Menu a SET I A A A A EXIT EXIT EXIT EXIT gt Operating up gt Serial ve probe pown Parameters DOWN In
2. 8 1 2 Digital Communication Interface The 7900 controller is capable of communicating with and being controlled by other equipment through the digital serial interface The RS 232 serial interface and IEEE 488 GPIB are standard With a digital interface the controller may be connected to a computer or other equipment This connection allows the user to set the set point temperature monitor the temperature and access any of the other controller functions all using remote communications equipment Communications commands are summarized in Table 3 on page 45 Hart Scientific recommends the use of shielded RS 232 and IEEE 488 GPIB cables for all remote communication Serial Communications The controller comes installed with an RS 232 serial interface RS 232 Cable Wiring for that allows serial digital com IBM PC and Compatibles munications over fairly long distances With the serial inter face the user may access any of Instrument Computer DTE Connector Connector the functions parameters and DB 9 Pin DB 9 Pin settings discussed in Section 8 1NC 1DcD with the exception of the BAUD 2RD e 2 RxD rate setting The serial interface es e pss operates with 8 data bits 1 stop 5 CNDe 5 GND bit and no parity 6NC 6 DSR 7RTS GENE s 7 RTS SE 8 CTS M 8 CTS Wiring ds ont The serial communications ca ble attaches to the controller through the DB 9 connector at Instru
3. Hart Scientific 9 7900 Temperature Controller User s Guide Rev 710801 Rev 711801 Limited Warranty Limitation of Liability Each product from Fluke Corporation Hart Scientific Division Hart is warranted to be free from de fects in material and workmanship under normal use and service The warranty period is 2 years for the Temperature Controller The warranty period begins on the date of the shipment Parts product repairs and services are warranted for 90 days The warranty extends only to the original buyer or end user cus tomer of a Hart authorized reseller and does not apply to fuses disposable batteries or to any other prod uct which in Hart s opinion has been misused altered neglected or damaged by accident or abnormal conditions of operation or handling Hart warrants that software will operate substantially in accordance with its functional specifications for 90 days and that it has been properly recorded on non defective me dia Hart does not warrant that software will be error free or operate without interruption Hart does not warrant calibrations on the Temperature Controller Hart authorized resellers shall extend this warranty on new and unused products to end user customers only but have no authority to extend a greater or different warranty on behalf of Hart Warranty support is available if product is purchased through a Hart authorized sales outlet or Buyer has paid the applicable international pri
4. SET to enter the menu The operating parameters menu contains the cutout reset mode and soak stability Cutout Reset Mode The cutout reset mode determines whether the cutout resets automatically when the system temperature drops to a safe value or must be manually reset by the operator The parameter is indicated by CEorSE i Cutout reset mode parameter IT Press SET to access the parameter setting Normally the cutout is set for manual mode AI TT 35 7900 Temperature Controller User s Guide 36 7 13 2 7 13 3 7 14 7 14 1 Soak Stability The soak stability controls the required stability of the well temperature The stability is in degrees Celsius The default is 0 1 C This parameter is indicated by 0 50 i Soak stability set for 0 50 C il To change the parameter setting press UP or DOWN and then SET to store the value Boost Temperature Offset The boost temperature offset allows the user to select the boost value At at which the boost heat turns off The boost heat switches off if the temperature is within the boost value At of the set point The boost heat switches on if the temperature falls below the set point by the boost value of plus 0 1 C The boost value is always in degrees C even if the unit is set to degrees F This parameter is indicated by ped bO 4 0 j Boost temperature offset set for 4 0 C EE IE To change the parameter setting pres
5. inside the instrument turn off the power and disconnect the power cord FLUIDS Fluids used in the system controlled by this instrument may produce noxious or toxic fumes under certain circumstances Consult the fluid manufacturer s MSDS Material Safety Data Sheet Proper ventilation and safety precautions must be observed The instrument is equipped with a soft cutout adjustable parameter and a hard cutout set at the factory Adjust the soft cutout according to fluid characteris tics or application As a guideline the soft cutout should be set 10 C to 15 C below the flash point of the fluid see Section 7 10 Cutout Insure that the flash point boiling point or other key fluid characteristics are not exceeded CAUTIONS To avoid possible damage to the instrument folow these guidelines DO use a ground fault interrupt device Operate the instrument in room temperatures as listed in Section 3 2 Environ mental Conditions Calibration constants should only be changed by trained personnel The correct setting of these parameters is important to the safety and proper operation of the instrument The Factory Reset Sequence should be performed only by authorized personnel if no other action is successful in correcting a malfunction You must have a copy of the most recent Report of Test to restore the test parameters The cooling outlet provided by the controller is for LN2 only DO NOT con nect mechanical cooling to t
6. of the temperature value are displayed at the right For example 25 00 C Process temperature in degrees Celsius The temperature display function may be accessed from any other function by pressing the EXIT button Reset Cut out If the over temperature cut out has been triggered then the temperature display will alternately flash Indicates cut out condition The message will continue to flash until the temperature is reduced and the cut out is reset The cut out has two modes automatic reset and manual reset and determines how the cut out is reset In automatic mode the cut out resets itself as soon as the temperature is lowered below the cut out set point In man ual reset mode the operator must reset the cut out after the temperature falls below the set point When the cut out is active and the cut out mode is set to manual c ESEE the display flashes cut out until the user resets the cut out To access the reset cut out function press the SET button SET Access cut out reset function The display indicates the reset function Cut out reset function Press SET once more to reset the cut out 23 7900 Temperature Controller User s Guide SET UP
7. serial interface parameters IEEE parameters and calibration pa rameters The groups are selected using the UP and DOWN keys and then pressing SET See Figure 6 on page 24 Probe Parameters RTD Sensor The probe parameter menu is indicated by PrObE Probe parameters menu Press SET to enter the menu The probe parameters menu contains the pa rameters Ry and ALPHA which characterize the resistance temperature rela tionship of the platinum control probe These parameters may be adjusted to 7 Controller Operation Operating Parameters 7 12 1 7 12 2 7 13 7 13 1 improve the accuracy of the bath This procedure is explained in detail in Sec tion 9 The probe parameters are accessed by pressing SET after the name of the pa rameter is displayed The value of the parameter may be changed using the UP and DOWN buttons After the desired value is reached press SET to set the parameter to the new value Pressing EXIT causes the parameter to be skipped ignoring any changes that may have been made Ro This probe parameter refers to the resistance of the control probe at 0 C Nor mally this is set for 100 000 ohms ALPHA This probe parameter refers to the average sensitivity of the probe between 0 and 100 C Normally this is set for 0 00385 C Operating Parameters The operating parameters menu is indicated by PAr i Operating parameters menu Mi Press
8. 0 00090 New vernier setting Next press EXIT to return to the temperature display or SET to access the temperature scale units selection Access scale units 7 Controller Operation Temperature Scale Unit 7 4 7 5 Temperature Scale Unit The user may set the temperature scale units of the controller to degrees Celsius C or Fahrenheit F The units are used in displaying the process tempera ture set point vernier proportional band and cut out set point The temperature scale units selection is accessed after the vernier adjustment function by pressing SET From the temperature display function access the units selection by pressing SET 4 times Un Scale units currently selected Press UP or DOWN to change the units Change units New units selected Press SET to accept the new selection and resume displaying the bath temperature SET Set the new units and resume temperature display Scan The scan control can be turned on or off and the scan rate can be set and en abled so that when the set point is changed the controller heats or cools at a specified rate degrees per minute until the new set point is reached With the 27 7900 Temperature Controller User s Guide 28 7 5 1 7 5 2 7 6 scan disabled the controller heats or cools at the maximum possible rate Scan Control The scan is controlled with the scan on off function that appears in the main menu
9. HALF 46 8 Digital Communication Interface Power Control Functions Table 5 Serial Interface Commands continued Command Command Returned Acceptable Command Description Format Example Returned Example Values Set serial duplex mode to full du plex f ull du f Set serial duplex mode to half du plex h alf du h Set serial linefeed mode Iffeed on of f ON or OFF Set serial linefeed mode to on Iffeed on If on Set serial linefeed mode to off If eed of f If of Calibration Menu WARNING changing the following calibration values may change the accuracy of the instrument Read CO calibration parameter c0 c0 c0 9 c0 0 Set CO calibration parameter to n cO n c0 0 999 9 to 999 9 Read CG calibration parameter cg cg cg 999 99 cg 406 25 Set CG calibration parameter to n cg n cg 406 25 999 9 to 999 9 Read low set point limit tllow tl t1 999 tl 80 Set low set point limit to n tllow n tl 80 999 9 to 999 9 Read high set point limit th igh th th 999 th 205 Set high set point limit to n th igh n th 205 999 9 to 999 9 Miscellaneous not on menus Read heater control function ft f1 fi f1 low or high fi low Set heater control function low or high Set heater control to low fi low fi low Set heater control to high f1 h igh fi high Read cooling control function f2 f2 f2 f2 on or off f2 on Set cooling control funct
10. Set temperature units to Celsius ufnits c u C Set temperature units to u nits f u f Fahrenheit Read scan function sc an SC scan ON or OFF scan ON Set scan function sc an on of f ON or OFF Turn scan function on sc an on sc on Turn scan function off sc an of f sc of Read scan rate sr ate sr srat 999 99 C or F min srat 10 0 C min Set scan rate to n degrees per sr ate n sr 5 1 to 100 C minute Read temperature t emperature t t 9999 99 C or F t 55 69 C Read temperature units u u U X uc Secondary Menu Read proportional band setting pr op band pr pb 999 9 pb 15 9 Set proportional band to n pr op band n pr 8 83 Depends on Configuration Read cutout setting c utout c c 9999 C or F c 620 C Set cutout setting c utout n r eset Set cutout to n degrees c utout n c 500 Temperature Range Reset cutout now c utout r eset c r Read heater power po wer po p 9999 po 1 duty cycle Ramp and Soak Menu Read number of programmable pn pn pn 9 pn 2 set points Set number of programmable pn n pn 4 1108 set points to n Read programmable set point psn ps3 psn 9999 99 C or F pst 50 00C number n 45 7900 Temperature Controller User s Guide Table 4 Serial Interface Commands continued Command Command Returned Acceptable Command Description Format Example Returned Example Values Set progra
11. max 115 VAC 210 50 60 Hz 15 8 A 1815 W Power max 115 VAC 10 50 60 Hz 16 A 1840 W Note Internal electronics require 0 2 A to operate System Fuses 20 A 250 V slow blow max Heater Fuses 20 A 250 V fast acting max Exterior Dimension 72 mm H x 172 mm W x 250 mm D 2 83 in x 6 75 in x 9 86 in Weight 4 0 kg 9 Ibs Safety OVERVOLTAGE Installation CATEGORY Il Pollution Degree 2 per IEC 61010 1 Environmental Conditions Although the instrument has been designed for optimum durability and trou ble free operation it must be handled with care The instrument should not be operated in an excessively dusty or dirty environment Maintenance and clean ing recommendations can be found in the Maintenance Section of this manual 7900 Temperature Controller User s Guide 10 The instrument operates safely under the following conditions ambient temperature range 5 50 C 41 122 F ambient relative humidity maximum 80 for temperature lt 31 C de creasing linearly to 50 at 40 C pressure 75kPa 106kPa mains voltage within 10 of nominal vibrations in the calibration environment should be minimized altitude less than 2 000 meters indoor use only 4 Quick Start Unpacking 4 1 4 2 4 2 1 4 2 2 4 2 2 1 Quick Start This section provides a brief summary of the steps required to set up and oper ate the 7900 temperature controller Thi
12. parame ter menu The menu is indicated by IEEE IEEE 488 parameters menu A Press SET to enter the menu IEEE 488 Address The IEEE 488 interface must be configured to use the same address as the ex ternal communicating device The address is indicated by Addr ESS IEEE 488 interface address Wuussaebassagauencasaees csasuceasens Press SET to access the address setting 7 Controller Operation Calibration Parameters 7 15 2 7 16 Adds ee Current IEEE 488 interface address Adjust the value with UP or DOWN and then use SET to set the address to the displayed value Add 15 New IEEE 488 interface address Termination The transmission termination character can be set to carriage return only line feed only or carriage return and linefeed Regardless of the option selected the controller interprets either a carriage return or a linefeed as a command termi nation during reception The termination parameter is indicated with EGS IEEE 488 termination Use SET to save the new selection Calibration Parameters The operator of the controller has access to a number of the calibration and setup constants namely CTO CO CG H L and SCO The calibration values are set at the factory and must not be altered The correct values are important to the accuracy of the controller Access to these parameters is available to the user only so that in the event that the controller
13. simplicity of maintenance have been a central theme in the product develop ment Therefore with proper care the instrument should require very little maintenance Avoid operating the instrument in dirty or dusty environments e A battery is used to maintain operating parameters in the unit All operat ing parameters including calibration parameters should be checked on a regular basis to insure accuracy and proper operation of the instrument See the troubleshooting section for the procedure on checking the status of the battery e If the outside of the controller becomes soiled it may be wiped clean with a damp cloth and mild detergent Do not use harsh chemicals on the sur face which may damage the paint e If a hazardous material is spilt on or inside the equipment the user is re sponsible for taking the appropriate decontamination steps as out lined by the national safety council with respect to the material MSDS sheets ap plicable to all fluids used in the baths should be kept in close proximity to the instrument e If the mains supply cord becomes damaged replace it with a cord with the appropriate gauge wire for the current of the system If there are any questions call Hart Scientific Customer Service for more information e Before using any cleaning or decontamination method except those rec ommended by Hart users should check with Hart Scientific Customer Service to be sure that the proposed method will not damage the e
14. the thermometer and compute the temperature error err which is the actual temperature minus the set point tem perature If for example the temperature is set for a lower set point of ty 50 C and the controller reaches a measured temperature of 49 7 C then the error is 0 3 C Next set the temperature for the upper set point ty and after stabilizing mea sure the temperature and compute the error erry For our example suppose the temperature was set for 150 C and the thermometer measured 150 1 C giving an error of 0 1 C Computing R and ALPHA Before computing the new values for Rg and ALPHA the current values must be known The values may be found by either accessing the probe calibration menu from the controller panel or by inquiring through the digital interface 49 7900 Temperature Controller User s Guide 50 The user should keep a record of these values in case they may need to be re stored in the future The new values Ry and ALPHA are computed by entering the old values for Ry and ALPHA the calibration temperature set points tj and ty and the temperature errors err and erry into the following equations R je Zeu ALPHA 1 R ty t rota 1 ALPHA t err 1 ALPHA t err ty tr ALPHA If for example R and ALPHA were previously set for 100 000 and 0 0038500 respectively and the data for tj ty err and erry were as given above then the new values Ry and ALPHA w
15. ERNAL CONTROL PROBE COOLING DEVICE IEEE 488 FLUKE CORPORATION HART SCIENTIFIC DIVISION www hartscientific com Figure 5 Back Panel 5 Parts and Controls Back Panel 5 6 7 The heater connector is the source of controlled power for the system heater This power is switched by the solid state relay to maintain a con stant temperature To connect the heater remove the top cover of the controller The heater cable is fed through the strain relief in the back panel and the spade connectors are attached to the appropriate terminals on the internal terminal block See Figure 3 The heater control for tem perature range is automatic The automatic system can be manually over ridden by turning the heater power to high using the front panel switch The stirrer motor connector is an auxiliary power socket for the stirrer motor This power is constant The combined current of the heater stirrer motor and LN cooling must not exceed 20 amps The stirrer motor ca ble is fed through the strain relief in the back panel and the spade con nectors are attached to the appropriate terminals on the terminal block inside the controller See Figure 3 The LN cooling device connector is the source of controlled power for the system LN cooling CAUTION The cooling power is for LN cooling only Do not use this connection for mechanical cooling 8 This power is switched by the solid state relay The LN cooling al
16. IRECT INCIDENTAL OR CONSE QUENTIAL DAMAGES OR LOSSES INCLUDING LOSS OF DATA WHETHER ARISING FROM BREACH OF WARRANTY OR BASED ON CONTRACT TORT RELIANCE OR ANY OTHER THEORY Since some countries or states do not allow limitation of the term of an implied warranty or exclusion or limitation of incidental or consequential damages the limitations and exclusions of this warranty may not apply to every buyer If any provision of this Warranty is held invalid or unenforceable by a court of com petent jurisdiction such holding will not affect the validity or enforceability of any other provision Fluke Corporation Hart Scientific Division 799 E Utah Valley Drive e American Fork UT 84003 9775 USA Phone 1 801 763 1600 Telefax 1 801 763 1010 E mail support hartscientific com www hartscientific com Subject to change without notice Copyright O 2005 Printed in USA Table of Contents 1 Before You Start 1 1 1 Symbols Used o cu see css om sm mk ets 1 1 2 Safety Information 2 1 2 1 WARNINGS et o3 iaci Bed He de ees NC Sik a we oe EUR 2 1 2 2 CAUTIONS 4X din de a cele a doc od 4 1 3 Authorized Service Centers 5 2 Introduction 7 3 Specifications and Environmental Conditions 9 3 1 SpecificatlOniS cogo RR oe pe X E RE ee est 9 3 2 Environmental Conditions 9 4 Quick Sarlo each S
17. P DOWN or EXIT indicates the panel button to press while the dotted box indicates the display reading on the front panel Explanation of the button function or display reading is written at the right To view or set the temperature set point proceed as follows The front panel LED display normally shows the actual process temperature Section 7 3 explains in detail how to set the temperature set point on the con troller using the front panel keys The procedure is summarized here 1 Press SET twice to access the set point value 15 7900 Temperature Controller User s Guide 16 2 Press UP or DOWN to change the set point value 3 Press SET to accept the new set point and to display the vernier value 4 Press EXIT to return to the temperature display When the set point temperature is changed the system heats or cools until the new set point is reached The over temperature cut out should be correctly set for added safety See Section 7 10 To obtain optimum control stability adjust the proportional band as discussed in Section 7 9 5 Parts and Controls Front Panel 5 Parts and Controls 5 1 Front Panel The following controls and indicators are present on the controller front panel see Figure 4 below 1 the digital LED display 2 the control buttons 3 the controller on off power switch 4 the control indicator light 5 the heater select switch and 6 the cooling power s
18. TC PROBE Insert the probe into the bath or system being controlled 4 2 5 Power Connect the controller power cord to a power source of the appropriate voltage and current rating see Section 3 1 Specifications 4 2 6 Fuses 14 CAUTION Never use this instrument in a system that uses more power or current as listed in Section 3 1 Specifications The controller is shipped from the factory with fast acting fuses rated for the maximum capacity of the instrument Tf the controller is connected to a system which uses less than 10 amps the fuses will need to be changed in order to be correct for the system Once the controller is connected in the system the system current needs to be measured or calculated and the appropriate fuse size and characteristics selected Gener ally the fuse selected is rated at 125 of the maximum current of the system The time current characteristics of the fuse are selected by the application Usually fast acting fuses are selected systems without a high in rush current i e hot calibration baths Time delay or slow blow fuses are selected for sys tems with a high in rush current i e cold calibration baths Refer to the fuseology section of your fuse catalog for help in determining fuse size and characteristics or contact an Authorized Service Center see Section 1 3 for as sistance Once the correct fuse characteristics and rating of the fuses have been selected and the appropriate fuses placed in
19. Troubleshooting may require the assistance of a technician with at least a basic understanding of electronics If the controller seems to be faulty or the problem cannot otherwise be solved then contact a Hart Scientific Authorized Service Center see Section 1 3 NOTE It is assumed that the controller is being used to control a calibra tion bath Problem Possible Causes and Solutions The heater indicator LED The problem may be either insufficient heating or no heating at all Insufficient stays red but the temper heating may be caused by the amount of cooling to the system being greater ature does not increase than the amount of heat the heater is capable of supplying Check that the heater is operational using a clamp on ammeter to measure the current to the heater If the heater is receiving current but not heating enough either replace the heater with one of greater rating but less than 20 A or decrease the amount of cooling to the system If the heater is not receiving power at all use a voltmeter to verify that voltage is present at the heater connection on the internal terminal block If voltage is present check the heater for correct wiring An ohm meter may help to find a discontinuity in the wiring Check for a shorted heater The solid state relay may not be operating and needs to be replaced Contact an Authorized Service Center If the heaters are not energized check the heater fuses Replace if the fuses are blown I
20. after the set point function ScRnz n Scan function on Press SET to accept the present setting and continue SET Accept scan setting Scan Rate The next function in the main menu is the scan rate The scan rate can be set from 1 to 100 C min The maximum scan rate however is actually limited by the natural heating or cooling rate of the instrument which is often less than 100 C min especially when cooling The scan rate function appears in the main menu after the scan control function The scan rate units are in degrees per minute degrees C or F depending on the selected units Sr 10 0 Scan rate in C min Press SET to accept the new scan rate and continue SET Accept scan rate Ramp and Soak Program The ramp and soak program feature allows the user to program a number of set points and have the controller automatically cycle between the tempera tures holding at each for a determined length of time The user can select one of four different cycle functions The program parameter menu is accessed by pressing SET and then UP 1080 00 j Well temperature AUTO O d Access program menu 7 Controller Operation Ramp and Soak Program 7 6 1 7 6 2 Prob Program menu Press SET to enter the program menu SET Enter program menu Number of Program Set points The first parameter in the program menu is the number of set points to cycle through Up to 8 set points can be used i
21. anual Otherwise the protection provided by the instrument may be impaired Refer to the safety information in Table 2 The following definitions apply to the terms Warning and Caution e WARNING identifies conditions and actions that may pose hazards to the user e CAUTION identifies conditions and actions that may damage the in strument being used WARNINGS To avoid personal injury follow these guidelines GENERAL DO NOT use the instrument for any application other than calibration work The instrument was designed for temperature calibration Any other use of the instrument may cause unknown hazards to the user DO NOT use the instrument in environments other than those listed in the user s guide Follow all safety guidelines listed in the user s manual Calibration Equipment should only be used by Trained Personnel If this instrument is used in a manner not specified by the manufacturer the protection provided by the instrument may be impaired If the instrument is used to control a calibration heat source insure the heater is wired correctly to the corresponding position on the internal strip as labeled The heater will heat continually if the heater and stirrer power are swapped see Figure 3 on page 13 1 Before You Start Safety Information Before initial use or after transport or after storage in humid or semi humid environments or anytime the dry well has not been energi
22. ar fluid used in the bath The bath should only be operated well below the upper tem perature limit of the liquid or device inserted into the liquid In addition the cut out temperature should also be set below the upper limit of the fluid Setting the temperature involves three steps 1 select the set point memory 2 adjust the set point value and 3 adjust the vernier if desired Programmable Set points The controller stores 8 set point temperatures in memory The set points can be quickly recalled to conveniently set the system to a previously programmed temperature To set the temperature one must first select the set point memory This function is accessed from the temperature display function by pressing SET The number of the set point memory currently being used is shown at the left on the display followed by the current set point value 25 00 L Process temperature in degrees Celsius SET Access set point memory i 25 0 Set point memory 1 25 0 C currently used To change the set point memory press UP or DOWN Increment memory 4 40 0 New set point memory 4 40 0 C Press SET to accept the new selection and access the set point value SET Accept selected set point memory Set point Value The set point value may be adjusted after selecting the set point memory and 25 7900 Temperature Controller User s Guide 26 7 3 3 pressing SET The set point value is displayed with the
23. ay The controller is equipped with an RS 232 serial and an IEEE 488 GPIB digital interface for remote op eration Operation of the controller using the front control panel is discussed in Section 8 Operation using the digital interface is discussed in Section 9 When the controller is set to a new set point the system heats or cools to the new temperature Once the new temperature is reached it usually takes 10 15 minutes for the temperature to settle and stabilize There may be a small over shoot or undershoot of about 0 5 C or more depending on the system and pro portional band 7 Controller Operation Process Temperature 7 1 7 2 Controller Operation This section discusses in detail how to operate the temperature controller using the front control panel Using the front panel key switches and LED display the user may monitor the process temperature set the temperature set point in de grees C or F monitor the heater output power adjust the controller proportional band set the cut out set point and program the probe calibration parameters operating parameters serial and IEEE 488 interface configuration and control ler calibration parameters Operations of the functions are shown in the flowchart summarized in Figure 6 Process Temperature The digital LED display on the front panel allows direct viewing of the process temperature This temperature value is what is normally shown on the display The units C or F
24. cations may be programmed to 300 600 1200 2400 4800 or 9600 baud The baud rate is pre programmed to 2400 baud Use UP or DOWN to change the baud rate value Press SET to set the BAUD rate to the new value or EXIT to abort the operation and skip to the next parameter in the menu Sample Period The sample period is the next parameter in the menu and prompted with SAMPLE The sample period is the time period in seconds between tempera ture measurements transmitted from the serial interface If the sample rate is set to 5 the instrument transmits the current measurement over the serial interface approximately every five seconds The automatic sampling is disabled with a sample period of 0 Press SET to choose to set the sample period Adjust the period with UP or DOWN and then use SET to set the sample rate to the displayed value Duplex Mode The next parameter is the duplex mode indicated with a UP L The duplex mode may be set to half duplex HALF or full duplex FULL With full duplex any commands received by the instrument via the serial interface are immediately echoed or transmitted back to the device of origin With half du plex the commands are executed but not echoed The default setting is full du plex The mode may be changed using UP or DOWN and pressing SET Linefeed The final parameter in the serial interface menu is the linefeed m
25. ce Hart reserves the right to invoice Buyer for importation costs of repairs replacement parts when product purchased in one country is submitted for repair in another country Hart s warranty obligation is limited at Hart s option to refund of the purchase price free of charge re pair or replacement of a defective product which is returned to a Hart authorized service center within the warranty period To obtain warranty service contact your nearest Hart authorized service center or send the product with a description of the difficulty postage and insurance prepaid FOB Destination to the nearest Hart au thorized service center Hart assumes no risk for damage in transit Following warranty repair the prod uct will be returned to Buyer transportation prepaid FOB Destination If Hart determines that the failure was caused by misuse alteration accident or abnormal condition or operation or handling Hart will provide an estimate or repair costs and obtain authorization before commencing the work Following repair the product will be returned to the Buyer transportation prepaid and the Buyer will be billed for the repair and return transportation charges FOB Shipping Point THIS WARRANTY IS BUYER S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF ALL OTHER WARRANTIES EXPRESS OR IMPLIED INCLUDING BUT NOT LIMITED TO ANY IM PLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE HART SHALL NOT BE LIABLE FOR ANY SPECIAL IND
26. ch of the four program mode settings Press SET to continue Table 2 Program mode setting actions Function Action 1 Up Stop 2 Up Down Stop 3 Up Repeat 4 Up Down Repeat Save new setting 7 Controller Operation Secondary Menu 7 6 5 7 7 7 8 Program Control The final parameter in the program menu is the control parameter You may choose between three options to either start the program from the beginning continue the program from where it was when it was stopped or stop the program PA O Press SET to activate the new program control command and return to the temperature display SET Activate new command Secondary Menu Functions which are used less often are accessed within the secondary menu Pressing SET and EXIT simultaneously and then releasing accesses the secondary menu The first function in the secondary menu is the heater power display See Figure 6 on page 24 Heater Power The temperature controller controls the temperature of the well by pulsing the heater on and off The duty cycle or the ratio of heater on time to the pulse cy cle time determines the total power being applied to the heater This value may be estimated by watching the red green control indicator light or may be read directly from the digital display By knowing the amount of heating the user can tell if the system is heating up to the set point cooling down or controlling at a constant tem
27. e Part number Power Resistance 00910 0125 0001 260 440 W 50 30 Ohms 00910 0126 0001 825 825 W 16 16 Ohms 00910 0126 0002 825 825 W 16 16 Ohms 00913 0072 0001 500 500 W 28 28 Ohms To connect the heater perform the following steps after removing the top cover of the controller four screws Be sure the heater cable is adequate for the amount of current required and that the heater is wired correctly and safely 1 The heater cable has 4 wires labeled C D E and G Determine whether the heater configuration uses G as a ground connection or G as one leg of the High heater by measuring the resistance from the spade connectors a The PRESENT heater assembly configuration Figure 2 uses G as a ground connection b The OLD heater assembly configuration Figure 1 uses G as one leg of the High heater G D E C Figure 1 Old heater configuration Figure 2 Present heater configuration 4 Quick Start Installation 2 Feed the wires through the strain relief labeled HEATER and route them to the terminal block 3 If you have the PRESENT heater assembly configuration Figure 2 connect all the wires as labeled on the terminal block 4 If you have the OLD heater assembly configuration Figure 1 connect the D and G wires together into the terminal slot labeled D Connect the rest of the wires as labeled There is no direct ground connection through the heater wires Instead the assembly will be grounded through th
28. e flow chute assembly 5 The heater hookup is complete 4 2 2 2 Stir Motor Connection Connect the stirring device to the back of the controller through the strain relief labeled STIR MOTOR Secure the stirrer to the terminal block at the termi nals marked A B and G for the stirrer See Figure 3 4 2 2 3 LN Connection Connect the LN cooling through the strain relief labeled COOLING DE VICE Secure the LN cooling to the terminal block at the terminals marked Heater LN Cooling Stir Motor 1OATHO2 3404 AATA3H XAM eTTAW 00T ABBA MID ML IDE IDE ID e a 2 e e sH 08 DAV 211 XAM IMA 0S Figure 3 Terminal Block 13 7900 Temperature Controller User s Guide R S and T for cooling DO NOT attach mechanical cooling through the controller A CAUTION Be sure that the combined current of the heater stirrer and LN cooling does not exceed 20 amps 4 2 3 Control Probe Connect the control probe into the socket at the back of the controller labeled CONTROL PROBE see Figure 5 Insert the probe into the bath or system to be controlled For best stability and response time the control probe should be located in close proximity to the heater Observe the maximum temperature rat ing of the probe and be careful it is not exceeded 4 2 4 Thermocouple Probe Connect the thermocouple cut out probe to the back of the controller to the connector labeled
29. er s Guide 60 12 3 Attaching the Probe Adapter 1 Remove the locking collar from the adapter 2 Place the guide tube through the flow chute cover plate If you are plac ing the adapter in the control probe hole the small washer acts as a spacer to center the adapter If you drilled the hole for the TC as outlined above discard the small spacer washer for the TC adapter 3 Slide the large washer and locking collar over the guide tube Hold all pieces tightly as the locking set screw is tightened The collar should be snugly compressed so that the adapter does not move in the hole 12 4 Inserting the Probes Replace the cover plate and flow chute on the bath 2 Insert the probes in the adapters
30. ervice Center Instrimpex Room 2301 Sciteck Tower 22 Jianguomenwai Dajie Chao Yang District Beijing 100004 PRC CHINA Phone 86 10 6 5 12 3436 Telefax 86 10 6 5 12 3437 E mail xingye han fluke com cn Fluke South East Asia Pte Ltd Fluke ASEAN Regional Office Service Center 60 Alexandra Terrace 03 16 The Comtech Lobby D 118502 SINGAPORE Phone 65 6799 5588 Telefax 65 6799 5588 E mail antngOsinga fluke com When contacting these Service Centers for support please have the following information available e Model Number e Serial Number e Voltage e Complete description of the problem 2 Introduction Introduction The Hart Scientific Model 7900 is a solid state temperature controller specifi cally designed to control the temperature of Rosemount designed temperature calibration baths The unique combination of analog and digital electronic cir cuitry provides exceptional accuracy and stability together with ease of opera tion and programmability Temperature sensing is done with a 4 wire 100 ohm platinum resistance probe that plugs into the back of the controller To maintain a constant temperature the controller adjusts the pulses of power supplied to the heater by means of a solid state relay The 7900 controller can be easily programmed via the four button front panel or by the serial or IEEE interface Programming allows the user to set the con trol temperature temperature scale units to C o
31. eters 1 Power off the instrument 2 Disconnect the instrument from AC power for 10 seconds 3 Reconnect the AC power and power on the instrument 4 If the display shows 1 17 and or the cycle count shows a low number such as 0002 the battery is spent and should be replaced Contact an Authorized Service Center for assistance 5 After replacing the battery you must reprogram the calibration and user ad justable parameters into the controller 57 12 Appendix 910 Bath Probe Adapter Instructions TC Cut Out 12 12 1 12 2 Appendix 910 Bath Probe Adapter Instructions Your new 7900 Controller for your Rosemount designed bath has a different size control PRT and an additional thermocouple TC cutout TC Cut Out Your Rosemount bath was not originally provided with a TC cutout Therefore provisions will have to be made to add this to the bath May we suggest the following 1 There is adequate space on the cover plate of the bath exactly across from the control probe to add the TC 2 Remove the plate and flow chute from the bath to keep metal shavings out of the bath 3 Drill a hole in the plate using at least a 265 drill bit 17 64 4 Attach the probe adapter to the plate Adapter Guide Tube Locking Collar Figure 10 Probe Adapter Control Probe 1 Remove your Rosemount control probe 2 Remove the Swadgelok fitting from the cover plate 59 7900 Temperature Controller Us
32. f the controller is determined by component selection and cannot be set by the user This value is fixed at approximately 300 seconds The proportional band adjustment can be accessed within the secondary menu Press SET and EXIT to enter the secondary menu and show the heater power Then press SET twice to access the proportional band ser exa Access heater power in secondary menu To change the proportional band press UP and DOWN boul Decrement display x To store the new setting and access the cut out set point press SET Press EXIT to exit out of the secondary menu Accept the new proportional band setting Cutout As a protection against software or hardware fault shorted heater triac or user error the controller is equipped with an adjustable heater cutout device that shuts power off to the heater if the system temperature exceeds a set value This protects the heater and system materials from excessive temperatures The cut out temperature is programmable by the operator from the front panel of the controller The cutout temperature must always be set below the upper tempera ture limit of the bath fluid If the cutout is activated because of excessive temperature power to the heater shuts off and the system cools The system cools until it reaches a few degrees below the cutout set point temperature At this point the action of the cutout is determined by the setting of t
33. f the fuses blow a second time contact an Authorized Service Center 55 7900 Temperature Controller User s Guide 56 Problem Possible Causes and Solutions The controller display flashes CUT 0UT and the heater does not operate The display will flash CUT OUT alternately with the process temperature If the process temperature displayed seems to be grossly in error then also con sult the problem The display flashes CUT OUT and incorrect process temper ature below A problem with the thermocouple probe the cutout operation or the cutout circuitry may cause the cutout to remain in this condition Check that the thermocouple probe is plugged into the controller and wired cor rectly Check that the probe temperature is well below the programmed set point If not then reset the cutout temperature to a value well above the probe temperature or wait for the temperature to cool well below the cutout set point If the cutout is set for manual reset mode then after the temperature cools the user must also manually reset the cutout according to the directions in this manual under the section on the cut out If everything appears OK the electronic hardware may have developed a fail ure Contact an Authorized Service Center The display flashes CUT OUT and incor rect process temperature The problem may be that the controller s voltmeter circuit is not functioning properly A problem could exi
34. for a while then cools The gain is probably too high causing the system to oscillate Lower the gain until the oscillation stops In some systems with large mass and slow response the gain must be lowered significantly to achieve steady control without oscilla tion If the gain is set as low as 1 and the system still oscillates the gain range may need to be changed Contact an Authorized Service Center see Section 1 3 The controller erratically heats then cools control is unstable If both the process temperature and output power do not vary periodically but in a very erratic manner the problem may not be oscillation due to instability but excess noise in the system Noise due to the control sensor should be less than 0 001 C However if the probe has been damaged an intermittent short may have developed causing erratic behavior Intermittent shorts in the heater or electronic circuitry in the controller may also be a possible cause If feasible try replacing the probe or heater In fluid baths improper stirring and or uneven heating or cooling can also cause instability In solid systems stability is typically much poorer than in fluid sys tems because of the much slower system response time The response time can be optimized by placing the control probe as close as possible to the heater The heater heats continu ously and the stirrer mo tor stirs sporadically or not at all Check to see that the heater and stirrer m
35. g errors in data as described in The display flashes tUT OUT and incorrect process temperature above If the users own probe is used the calibration parameters namely R and AL PHA may need to be adjusted to more closely match the characteristics of the probe Calibration assistance may be obtained from an Authorized Hart Scien tific Service Center If the probe was purchased from Hart and the parameters all agree with the certification sheet but the controller does not meet the specifi cation then the controller may need to recalibrated If this is the case rough handling in shipping may have caused shock to the probe or sensitive electronic components Contact an Authorized Service Center see Section 1 3 The controller shows that the output power is steady but the process temperature is unstable The gain may be increased to achieve better control stability Normally the con troller is used with systems that have fairly quick response times and require narrow proportional bands In some systems with very slow response times the proportional band may need to be set to a value larger than what is normally al lowed with the controller Internal jumpers on the lower PC board allow the gain to be increased If this is necessary please contact an Authorized Service Cen ter see Section 1 3 for assistance 11 Troubleshooting Troubleshooting Problem Possible Causes and Solutions The controller alternately heats
36. he controller DO NOT operate this instrument in an excessively wet oily dusty or dirty en vironment or place in locations where hot or cold liquids are splashed on it Most probes have handle temperature limits Be sure that the probe handle tem perature limit is not exceeded in the air above the system controlled by this instrument The instrument and any thermometer probes used with it are sensitive instru ments that can be easily damaged Always handle these devices with care Do not allow them to be dropped struck stressed or overheated DO NOT use this instrument in a system that exceeds the current capability of the instrument as listed in Section 3 1 Specifications 1 Before You Start Authorized Service Centers 1 3 DO NOT replace fuse s with one of a higher current rating or type Always re place the fuse with one of the same rating voltage and type The current rating listed in Section 3 1 Specifications is the maximum for the instrument If the instrument is connected to a system which uses less than the maximum capabil ity of this instrument the fuses need to be changed in order to be correct for the system Once the instrument is connected to the system the system current needs to be measured or calculated and the appropriate fuse size and character istics selected Section 4 2 6 Fuses can be used as a guide for selecting a fuse Once the correct fuse type and rating is selected the following informat
37. he controller is precisely controlled Power is controlled by periodically switching the cooling on for a certain amount of time using a solid state relay The LN cooling alter nates with the heater power to maintain a constant temperature Temperature Controller Hart Scientific s unique hybrid digital analog temperature controller manipu lates the system temperature The controller offers the precise stability of an an alog temperature controller as well as the flexibility and programmability of a digital controller The temperature is monitored with a platinum resistance sensor in the control probe The signal is electronically compared with the programmable reference signal amplified and then passed to a pulse width modulator circuit which controls the amount of power applied to the bath heater As a secondary protection device the controller is also equipped with a sepa rate thermocouple temperature monitoring circuit that shuts off the heater if the temperature exceeds the cut out set point The controller allows the operator to set the set point temperature with high resolution set the cut out adjust the proportional band monitor the heater out put power and program the controller configuration and calibration parameters The controller may be operated in temperature units of degrees Celsius or Fahr enheit The controller is operated and programmed from the front control panel using the four key switches and digital LED displ
38. he cutout mode parameter The cutout has two modes automatic reset or manual reset If the mode is set to automatic the cutout automatically resets when the system temperature falls below the reset temperature allowing the system to heat up again If the mode is set to manual the heater remains disabled until the user manually resets the cutout The cutout set point may be accessed within the secondary menu Press SET and EXIT to enter the secondary menu and show the heater power Then press SET twice to access the cutout set point 33 7900 Temperature Controller User s Guide 34 7 11 7 12 SET fexr Access heater power in secondary menu A CO 2100 Cutout set point D AG BB To change the cutout set point press UP or DOWN Decrement display CG 96 New cutout set point To accept the new cutout set point press SET Accept cutout set point The next function is the configuration menu Press EXIT to resume display ing the temperature Controller Configuration The controller has a number of configuration and operating options and calibra tion parameters that are programmable via the front panel These are accessed from the secondary menu after the proportional band function by pressing SET The display prompts with ConFIG Press SET again to enter the first of five groups of configuration parameters probe parameters operating parameters
39. he serial interface approximately every five seconds The automatic sampling is disabled with a sample period of 0 The sample period is indicated by SAMPLE Serial sample period parameter Press SET to choose the sample period The current sample period value is displayed S5A 1 j Current sample period seconds Adjust the value with UP or DOWN and then use SET to set the sample rate to the displayed value EXIT does not store the new value 58 50 New sample period Duplex Mode The next parameter is the duplex mode The duplex mode may be set to full du plex or half duplex With full duplex any commands received by the controller via the serial interface are immediately echoed or transmitted back to the device of origin With half duplex the commands are executed but not echoed The du plex mode parameter is indicated by 37 7900 Temperature Controller User s Guide 38 7 14 4 7 15 7 15 1 sion asador TITI LS Ggcecsbacagatcacastassesensyeesanes Linefeed The final parameter in the serial interface menu is the linefeed mode This pa rameter enables on or disables off transmission of a linefeed character LF ASCII 10 after transmission of any carriage return The linefeed parameter is indicated by il A A IEEE 488 Parameters With an IEEE 488 GPIB interface the user may set the IEEE 488 interface ad dress and the transmission termination character within the IEEE 488
40. ion on or off Set cooling control on f2 on f2 on Set cooling control off f2 o ff f2 off Read firmware version number ver sion ver ver 9999 9 99 ver 7900 1 00 Read structure of all commands h elp h list of commands Read all extended operating all all list of commands parameters Legend Note Optional Command data Alternate characters or data Returns either information n Numeric data supplied by user may be entered in decimal or exponential notation 9 Numeric data returned to user x Character data returned to user When DUPLEX is set to FULL and a command is sent to READ the command is returned followed by a carriage return and linefeed Then the value is returned as indicated in the RETURNED column 47 7900 Temperature Controller User s Guide the parameter to 1 turns the cooling on F2 with no value returns the cur rent state of the cooling power control Table 6 Power Control Functions Function Command 0 1 High Heat F1 low high Cooling F2 off on 48 9 Calibration Procedure RTD Probe Calibration 9 1 9 1 1 Calibration Procedure In some instances the user may want to calibrate the controller to improve the temperature set point accuracy Calibration is done by adjusting the controller probe calibration constants Ry and ALPHA so that the process temperature as measured with a standard thermometer agrees more closely with the set point The thermome
41. ion is applicable The instrument is equipped with operator accessible fuses If a fuse blows it may be due to a power surge or failure of a component Replace the fuses once If a fuse blows a second time it is likely caused by failure of a component As a test disconnect the output device heater and apply power to the rest of the system Check to see if the fuse s blow If the fuse s blow only when an output device heater stirrer etc is connected the fault may be in the system component If not contact an Authorized Service Center see Section 1 3 If a mains supply power fluctuation occurs immediately turn off the instru ment Power bumps from brown outs and black outs can damage the system Wait until the power has stabilized before re energizing the instrument For best accuracy the instrument needs to be calibrated with the system it controls Authorized Service Centers Please contact one of the following authorized Service Centers to coordinate service on your Hart product Fluke Corporation Hart Scientific Division 799 E Utah Valley Drive American Fork UT 84003 9775 USA Phone 1 801 763 1600 Telefax 1 801 763 1010 E mail support hartscientific com Fluke Nederland B V Customer Support Services Science Park Eindhoven 5108 5692 EC Son NETHERLANDS 7900 Temperature Controller User s Guide Phone 31 402 675300 Telefax 31 402 675321 E mail ServiceDesk fluke nl Fluke Int l Corporation S
42. le Period a ses 3 403 dos Ed Ra Sete Hoe P P EE x3 37 7 14 3 Duplex Mode za ded de a x du we ROS e be sito 37 7 14 4 Linefeedi y a vow Ra Rs ete emule dra RR ont ui 38 715 TEEE 488 Parameters 38 735 1 IEBE 488 Address 4 2523 da sm Roe a BE a Sos AOR EC ede dte 38 7 15 2 Termination j lt 4 4044 ahd Roe pod oe oh doped on dod end x 39 7 16 Calibration Parameters 39 7 16 1 CTO y e x Mo de BeOS aw REX Rok xU US lE GP S UE de mE 40 7 16 2 CO and CG csm x 80e nb nce y Ree tie E EP eS 40 7 16 3 BH and z us us duae ease desee xe e ede ede dre E o 40 7 16 4 SCO ea bods he rese ars aaa mar RSS GS 40 8 Digital Communication Interface 41 8 1 Serial Communications 8 1 1 WING eck ago ede os P xe eodem dob de qos do xe 8 1 2 Sep zoe do pee c ROS AS E dale Sale X din SIL Baud Rate so sites o em SS oe es ERIS cade st E E 81 2 2 Sample Penod sU SA X eer AC dope ade RS 8 1 2 3 Duplex Mode is msn ae rr R s n ae dames 8 124 Lin fe d 254 4 4 he iki a due ny ER ad be ROS 8 1 3 Serial Operations s s e dem dd a hoe Ode dom de 8 1 4 IEEE 488 Communication 8 1 4 1 Setup and Address Selection 8 14 2 IEEE 488 Op ration eoo Ae Re we A 8 2 Interface Commands 8 3 Power Control Functions 8 3 1 Heater Control uel aem Ede x Ra do Yee aac 8 3 2 Co
43. ller User s Guide 44 8 3 8 3 1 8 3 2 rameter or display a parameter depending on whether or not a value is sent with the command following a character For example will return the current set point and s 150 0 will set the set point to 150 0 degrees CAL S In the following list of commands characters or data within brackets and are optional for the command A slash denotes alternate characters or data Numeric data denoted by n may be entered in decimal or exponential notation Characters are shown in lower case although upper case may be used Spaces may be added within command strings and will simply be ignored Backspace BS ASCII 8 may be used to erase the previous character A termi nating CR is implied with all commands Power Control Functions The digital interface is capable of controlling the heating and cooling functions so that the controller can be remotely operated at any temperature within the range of the bath To allow the interface to control the heating and cooling the front panel controls are disabled by switching the heater switch to LOW and the cooling switch to OFF Otherwise the interface would not be able to switch these functions off The 7900 controller has 2 control functions with the digital interface These are heater power high low and cooling on off See Table 6 Heater Control The 7900 controller automatically switches to high heat whene
44. ment Computer DTE I Connector Connector the back panel Figure 8 shows DB 9 Pin DB 25 Pin the pin out of this connector es and suggested cable wiring To 2RxD 2TxD eliminate noise the serial cable 3TxD 3RxD should be shielded with low re 2 ils sistance between the connector ND ZEND a 0 SA DB 9 and the shield 7RTS JL zewp 8CTS 8DCD Setup 9NC 20DTR Before operation the serial in terface must first be set up by programming the BAUD rate Figure 8 Serial Communications Cable Wiring 41 7900 Temperature Controller User s Guide 42 8 1 2 1 8 1 2 2 8 1 2 3 8 1 2 4 and other configuration parameters These parameters are programmed within the serial interface menu To enter the serial parameter programming mode first press EXIT while pressing SET and release to enter the secondary menu Press SET repeat edly until the display reads P Ar Press UP until the serial interface menu is indicated with 5Er 1AL Finally press SET to enter the serial parameters menu In the serial interface parameters menu are the BAUD rate the sample rate the duplex mode and the linefeed parameter Baud Rate The baud rate is the first parameter in the menu The display prompts with the baud rate parameter by showing b A U d Press SET to choose to set the baud rate The current baud rate value is displayed The baud rate of the serial communi
45. mmable set point num psn n ps3 50 1 to 8 Instru ber nto n ment Range Read program set point soak pt pt ti 999 ti 5 time Set program set point soak time ptzn pt 5 0 to 500 to n minutes Read program control mode pc pc prog OFF or ON prog OFF Set program control mode pc g o s top c ont GO or STOP or CONT Start program Pc g o or pc on pc g Stop program pc s top pc s Continue program pcec ont pc c Read program function pf pf pf 9 pf 3 Set program function to n pf n pf 2 1104 Configuration Menu Probe Menu Read RO calibration parameter r 0 r r0 999 999 r0 100 578 Set RO calibration parameter to n r 0 n r 100 324 98 0 to 104 9 Read ALPHA calibration al pha al al 9 9999999 al 0 0038573 parameter Set ALPHA calibration parameter al pha n al 0 0038433 00370 to ton 00399 Operating Parameters Menu Read cutout mode cm ode cm m 000 m AUTO Set cutout mode cm ode r eset a uto RESET or AUTO Set cutout to be reset manually cm ode r eset cm r Set cutout to be reset cm ode a uto cm a automatically Read stability ts ts ts 9 9 ts 0 5 Set soak stability to n degrees ts n ts 1 01 to 4 99 C Read boost temperature offset bt bt bt 9 99 bt 4 0 Set boost temperature offset bt n bt 9 0 to 9 99 Serial Interface Menu Read serial sample setting sa mple sa sa 9 sa 1 Set serial sampling setting to n sa mple n sa 0 0 to 4000 seconds Set serial duplex mode du plex f ull h alf FULL or
46. n a ramp and soak program pd Pnz3 i New number of program set points Press SET to continue Press EXIT to ignore any changes made to the parameter Save new setting Set points The next parameters are the program set points a A C 165 00 j New set point value NIMPBISEIIRSRSIRRR XR L TETE Press SET to save the new set point value The other set points can also be set in the same manner Once the set points are programmed as desired press EXIT to continue exr Continue to next menu function 29 7900 Temperature Controller User s Guide 30 7 6 3 7 6 4 Program Soak Time The next parameter in the program menu is the soak time This time in min utes is the time each program set points waits after settling before proceeding to the next set point The duration is counted from the time the temperature set tles to within a specified stability The stability requirement can be set in the parameter menu as explained in Section 6 13 4 The default is 0 1 C PE 15 Soak time in minutes Press SET to continue SET Save new setting Program Function Mode The next parameter is the program function or cycle mode There are four pos sible modes that determine whether the program scans up from set point 1 to n only or both up and down from set point n to 1 and also whether the pro gram stops after one cycle or repeats the cycle indefinitely Table 3 below shows the action of ea
47. n is because the power output changes very little with temperature and the controller cannot respond very well to changing conditions or noise in the system If the proportional band is too narrow the temperature may swing back and forth because the controller overreacts to temperature variations Best stability control is only possible when the proportional band is set for the opti mum width for the specific system configuration MAMAN A Proportional Band too Narrow Proportional Band too Wide Optimum Proportional Band Figure 7 Temperature fluctuations at various proportional band settings The optimum proportional band width depends on several factors including system heat transfer characteristics and heater probe positioning Thus the pro portional band width may require adjustment for best bath stability when any of these conditions change The proportional band width is easily adjusted from the front panel The width may be set to discrete values in degrees C or F depending on the selected units The optimum proportional bandwidth setting may be determined by monitoring the stability with a high resolution thermometer or with the controller percent output power display Narrow the proportional bandwidth to the point at which the process temperature begins to oscillate Increase the bandwidth from this point by multiplying the current value by 3 and entering this new value 7 Controller Operation Cutout 7 10 The integral time o
48. nter the second ary menu Press SET repeatedly until the display reaches Pr Ob E This is the menu selection Press UP repeatedly until the IEEE 488 interface menu is indicated with IEEE Press SET to enter the IEBE 488 parameter menu The IEEE 488 menu contains the IEEE 488 address parameter The IEEE 488 address is prompted with A d d r E55 Press SET to program the address The default address is 22 Change the device address if necessary to match the address used by the communication equipment by pressing UP or DOWN and then SET IEEE 488 Operation Commands may now be sent via the IEEE 488 interface to read or set the tem perature or access other controller functions All commands are ASCII charac ter strings and are terminated with a carriage return CR ASCII 13 Interface commands are listed below Interface Commands The various commands for accessing the controller functions via the digital in terfaces are listed in this section see Table 3 These commands are used with both the RS 232 serial interface and the IEEE 488 GPIB interface In either case the commands are terminated with a carriage return character The inter face makes no distinction between upper and lower case letters hence either may be used Commands may be abbreviated to the minimum number of letters that determines a unique command A command may be used to either set a pa 43 7900 Temperature Contro
49. nterface Commands continued 46 Serial Interface Commands continued 47 Power Control Functions 48 Calibration Example Platinum RTD Probe 51 Probe Adapter o ncaa ia a a a s 59 1 Before You Start Symbols Used 1 1 Before You Start Symbols Used Table 1 lists the International Electrical Symbols Some or all of these symbols may be used on the instrument or in this manual Table 1 International Electrical Symbols Symbol Description NU AC Alternating Current PS AC DC Battery Mm P Complies with European Union directives DC Double Insulated Electric Shock Fuse PE Ground Hot Surface Burn Hazard Read the User s Manual Important Information Off OPPOUPH On 7900 Temperature Controller User s Guide 1 2 1 2 1 Symbol Description Canadian Standards Association us OVERVOLTAGE Installation CATEGORY II Pollution Degree 2 per IEC1010 1 re fers to the level of Impulse Withstand Voltage protection provided Equipment of OVERVOLTAGE CATEGORY II is energy consuming equipment to be supplied from the fixed installation Examples include household office and laboratory appliances C TIC Australian EMC mark CAT I The European Waste Electrical and Electronic Equipment WEEE Directive 2002 96 EC mark Safety Information Use this instrument only as specified in this m
50. ode This pa rameter enables 9 n or disables 8 FF transmission of a linefeed charac ter LE ASCII 10 after transmission of any carriage return The default setting is with linefeed on The mode may be changed using UP or DOWN and pressing SET 8 Digital Communication Interface Interface Commands 8 1 4 1 8 1 4 2 8 2 Serial Operation Once the cable has been attached and the interface set up properly the control ler immediately begins transmitting temperature readings at the programmed rate The serial communications uses 8 data bits one stop bit and no parity The set point and other commands may be sent via the serial interface to set the temperature set point and view or program the various parameters The inter face commands are discussed in Section 9 2 All commands are ASCII charac ter strings terminated with a carriage return character CR ASCII 13 IEEE 488 Communication The IEEE 488 interface is a GPIB type communication bus that allows many instruments to be connected and controlled simultaneously To eliminate noise the GPIB cable should be shielded Setup and Address Selection To use the IEEE 488 interface first connect an IEEE 488 standard cable to the back of the controller Next set the device address This parameter is programmed within the IEEE 488 interface menu To enter the IEEE 488 parameter programming menu first press EXIT while pressing SET and release to e
51. oling Control xod o sa A IK X EUR 9 Calibration Procedure 9 1 RTD Probe Calibration 9 1 1 Calibration Points 42x ii ww Re a 9 1 2 Measuring the Set point Error 913 Computing Rand ALPHA 9 1 4 Calibration Example ss secreet eet pestea Tia 10 Maintenance 11 Troubleshooting 11 1 Troubleshooting 12 Appendix 910 Bath Probe Adapter Instructions IX TE CU QUE cece see eg e ge RY 12 2 Control Probes o OBS Ee Egi 12 3 Attaching the Probe Adapter 12 4 Inserting the Probes lii Figures and Tables Table 1 Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Table 2 Figure 7 Figure 8 Table 3 Table 4 Table 5 Table 6 Figure 9 Figure 10 International Electrical Symbols 1 Oldheaterconfiguration len 12 Present heater configuration 12 Terminal Block 24 go EORR a os 13 Front Control Panel 17 Back Panel o cga koe m ww PPR or Ro we y 3 UP Se Re 18 Controller Flow Chart 6 s s acea a RC OR Rw RR 24 Program mode setting actions 30 Temperature fluctuations at various proportional band settings 32 Serial Communications Cable Wiring 41 Serial Interface Commands 45 Serial I
52. otor are connected into the correct sockets on the back of the unit If not plug them in correctly If they are plugged in correctly contact an Authorized Service Center Power up The controller is equipped with internal operator accessible fuses If a fuse blows it may be due to a power surge or failure of a component Replace the fuse once DO NOT replace the fuse with one of a higher current rating Always replace the fuse with one of the same rating voltage and type If the fuse blows a second time it is likely caused by failure of a component part Disconnect the heaters stirrer motor and or LN Cooling Check to see if the fuse s blow Connect the heater stirrer motor and LN cooling one at a time Check each time to see if the fuse s blow If the fuse s blow only when the heater stirrer motor and or LN cooling are connected the fault may be in the system If not contact an Authorized Service Center see Section 1 3 The controller does not maintain controller pa rameters or parameters are reset each time the power to the unit is removed Note Before performing the memory check you need to record the controller calibration parameters found in the CAL menu of the instrument and any user adjusted parameters that you have changed such as the pro grammable set points and proportional band Memory Check Doing a memory check is the easiest way to verify the ability of the battery to maintain controller param
53. ould be computed as 100 193 and 0 0038272 re spectively Program the new values Ry and ALPHA into the controller Check the calibration by setting the temperature to t and ty and measuring the errors again If desired the calibration procedure may be repeated again to further im prove the accuracy Calibration Example The controller is to be used between 75 and 125 C and it is desired to calibrate the system as accurately as possible for operation within this range The current values for Rg and ALPHA are 100 000 and 0 0038500 respectively The cali bration points are chosen to be 80 00 and 120 00 C The measured tempera tures are 79 843 and 119 914 C respectively Refer to Figure 9 for applying equations to the example data and computing the new probe constants 9 Calibration Procedure RTD Probe Calibration RO 100 000 ALPHA 0 0038500 t 80 00 C measured t 79 843 C t 120 00 C measured t 119 914 C Compute errors err 79 843 80 00 C 0 157 C err 119 914 120 00 C 0 086 C Compute R e coe x 80 0 0157 x 120 0 120 0 80 0 Compute ALPHA 1 0 00385x120 0 0 157 1 0 00385 x 80 0 0 086 120 0 80 0 0 00385 1 00000 100115 ALPHA l 0 00385 0 0038387 Figure 9 Calibration Example Platinum RTD Probe 51 10 Maintenance 10 Maintenance The controller has been designed with the utmost care Ease of operation and
54. perature Monitoring the percent heater power lets the user know how stable the well temperature is With good control stability the per cent heating power should not fluctuate more than 5 within one minute The heater power display is accessed in the secondary menu Press SET and EXIT simultaneously and release The heater power is displayed as a percent age of full power exr Access heater power in secondary menu 100 Pct j Heater power in percent To exit out of the secondary menu press EXIT To continue on to the propor tional band setting function press SET 31 7900 Temperature Controller User s Guide 32 7 9 Proportional Band In a proportional controller such as this the heater output power is proportional to the well temperature over a limited range of temperatures around the set point This range of temperature is called proportional band At the bottom of the proportional band the heater output is 100 At the top of the propor tional band the heater output is 096 Thus as the temperature rises the heater power is reduced which consequently tends to lower the temperature back down In this way the temperature is maintained at a fairly constant value The temperature stability of the well and response time depend on the width of the proportional band See Figure 7 If the band is too wide the well tempera ture deviates excessively from the set point due to varying external conditions This deviatio
55. pikes from being transmitted to other equipment To turn on the controller switch the control panel power switch to the ON posi tion The LED display will begin to show the process temperature and the heater will turn on or off until the bath temperature reaches the programmed set point When powered on the control panel display will briefly show a four digit num ber This number indicates the number of times power has been applied to the controller Also briefly displayed is data that indicates the controller hardware configuration This data is used in some circumstances for diagnostic purposes Heater The power to the heater plugged into the controller is precisely controlled to maintain a constant system temperature Power is controlled by periodically switching the heater on for a certain amount of time using a solid state relay The front panel red green control indicator shows the state of the heater The control indicator glows red when the heater is on and glows green when the heater is off The indicator will pulse constantly when the controller is main taining a stable temperature The heater power automatically switches between low and high when the bath 1s being heated to a new temperature The automatic system can be overridden by turning the heater switch to HIGH power 21 7900 Temperature Controller User s Guide 22 6 4 6 5 LN Cooling The power to the LN cooling device plugged into the back of t
56. quip ment e Ifthe instrument is used in a manner not in accordance with the equip ment design the operation of the controller may be impaired or safety hazards may arise WARNING When checking the over temperature cutout be sure that the temperature limits of the system fluid are not exceeded Exceeding the tem perature limits of the system fluid could cause harm to the operator lab and instrument e The over temperature cutout should be checked every 6 months to see that it is working properly In order to check the user selected cutout follow the controller directions Section 7 10 for setting the cutout Both the manual and the auto reset option of the cutout should be checked Set the controller temperature higher than the cutout Check to see if the display flashes cutout and the temperature is decreasing 53 11 Troubleshooting Troubleshooting 11 11 1 Troubleshooting This section contains information on troubleshooting and a wiring diagram This information pertains to a number of bath models and certain specifics may not pertain to your model Troubleshooting In the event that the user of the 7900 temperature controller encounters diffi culty in operation this section may help to find and solve the problem Several possible problem conditions are described along with likely causes and solu tions If a problem arises please read this section carefully and attempt to un derstand and solve the problem
57. r F the proportional band and the calibration variables The process or actual temperature is continuously dis played on a bright green LED panel The percent heating power may also be monitored An added safety device the over temperature cut out is also programmable This built in feature protects the system from fault conditions causing excessive temperature by disabling the heater if the temperature sensed by a separate thermocouple probe exceeds the cut out set point Before using the 7900 con troller you should understand the proper setup and operation 3 Specifications and Environmental Conditions Specifications 3 1 3 2 Specifications and Environmental Conditions Specifications Temperature Range 100 C to 400 C 148 F to 752 F Accuracy 10 Stability 0 003 C depends on application Stabilization Time approximately 30 minutes depends on system design Control Probe 100 RTD 4 wire Resolution 0 0002 C F in high resolution mode Readout Switchable C or F Cooling Control LN2 automatic requires optional LN2 valve box Controller Hybrid Digital Analog controller with data retention Interface RS 232 and IEEE standard Fault Protection High temperature cutout Type K thermocouple input Sensor burnout and short protection Cutout Accuracy 10 C Combined Stir Motor Heater and LN2 Cooling Outputs
58. s UP or DOWN and then SET to store the value Serial Interface Parameters The serial RS 232 interface parameters menu is indicated by SEriRL Serial RS 232 interface parameters menu id The serial interface parameters menu contains parameters which determine the operation of the serial interface The parameters in the menu are baud rate sample period duplex mode and linefeed Baud Rate The baud rate is the first parameter in the menu The baud rate setting deter mines the serial communications transmission rate 7 Controller Operation Serial Interface Parameters 7 14 2 7 14 3 The baud rate parameter is indicated by bAUd Serial baud rate parameter Press SET to choose to set the baud rate The current baud rate value is then displayed 2400 Current baud rate The baud rate of the serial communications may be programmed to 300 600 1200 or 2400 baud 2400 baud is the default setting Use UP or DOWN to change the baud rate value 4800 b i New baud rate Press SET to set the baud rate to the new value or EXIT to abort the opera tion and skip to the next parameter in the menu Sample Period The sample period is the next parameter in the serial interface parameter menu The sample period is the time period in seconds between temperature measure ments transmitted from the serial interface If the sample rate is set to 5 the in strument transmits the current measurement over t
59. s memory fails the user may re store these values to the factory settings The user should have a list of these constants and their settings with the manual WARNING DO NOT change the values of the controller constants from the factory set values The correct setting of these parameters is important to the safety and proper operation of the system The calibration parameters menu is indicated by CAL Calibration parameters menu Press SET five times to enter the menu 39 7900 Temperature Controller User s Guide 40 7 16 1 7 16 2 7 16 3 7 16 4 CTO Parameter CTO sets the calibration of the over temperature cutout This param eter is not adjustable by software but is adjusted with an internal potentiometer CO and CG These parameters calibrate the accuracy of the controller set point These are programmed at the factory when the controller is calibrated Do not alter the value of these parameters If the user desires to calibrate the controller for im proved accuracy then calibrate Ry and ALPHA according to the procedure given in Section 9 H and L These parameters set the upper and lower set point limits of the controller These parameters should not be set beyond the safe operating temperature lim its of the system SCO This parameter is used at the factory for testing purposes and SHOULD NOT be altered by the user 8 Digital Communication Interface Serial Communications 8 1 8 1 1
60. s on a heat resistant surface or rack until they are at room temperature Fires and severe burns may result if personnel fail to observe safety precautions ELECTRICAL HAZARD These guidelines must be followed to ensure that the safety mechanisms in this instrument will operate properly The instrument must be plugged into an ap propriate outlet as specified in Section 2 1 Specifications on page 7 Also the current and voltage capability of the instrument must not be exceeded The power cord of the instrument is equipped with a three pronged grounding plug for your protection against electrical shock hazards It must be plugged directly into a properly grounded three prong receptacle The receptacle must be in stalled in accordance with local codes and ordinances Consult a qualified elec trician DO NOT use an extension cord or adapter plug DO use a ground fault interrupt device This system that is controlled by this instrument may contain a fluid A ground fault device is advised in case fluid is present in the electrical system and could cause an electrical shock 7900 Temperature Controller User s Guide 1 2 2 Always replace the power cord with an approved cord of the correct rating and type If you have questions contact a Authorized Service Center see Section 1 3 High voltage is used in the operation of this equipment Severe injury or death may result if personnel fail to observe the safety precautions Before working
61. s section should be used as a general overview and reference not as a substitute for the remainder of the manual Please read Sections 4 2 though 6 carefully before operating the controller Unpacking Unpack the controller carefully and inspect it for any damage that may have oc curred during shipment If there is shipping damage notify the carrier immediately An RTD control probe and a thermocouple cut out probe should have been pur chased along with the controller Verify that the following components are present e 7900 Controller with attached power cord e Control Probe e Thermocouple Probe e User s Guide e Probe Adapter 2 e Extra power cord 15 Amp Installation Setup The 7900 controller is a precision instrument that should be located in an ap propriate environment The location should be free from excessive dirt mois ture vibration or temperature variations There should be no present danger of spilled liquids Heater Stirrer LN Cooling In order to access the terminal block connectors Figure 3 for the heater stirrer motor and LN Cooling remove the top cover of the controller Heater Connection CAUTION READ THIS ENTIRE PROCEDURE BEFORE CONNECT ING THE HEATERS 11 7900 Temperature Controller User s Guide 12 This controller can be used with the following heater assemblies If the heater assembly that you are using is not listed please call Hart Scientific Customer Service for assistanc
62. st with the memory back up battery If the battery power is insufficient to maintain the memory data may become scrambled causing all sorts of strange symptoms A large static discharge may also affect data in memory The memory may be reset by holding the SET and EXIT keys down while power to the controller is switched on The display will show 1 ni E indicating the memory is being initialize At this point each of the controller parameters and calibration constants must be reprogrammed into memory If the problem is solved but reoccurs the battery should be replaced If the problem is not fixed there may be a failed electronic component In either case contact an Authorized Service Center see Section 1 3 The displayed process temperature is in error and the controller re mains in the cooling or heating state at any set point value A typical cause of this problem is the control probe The probe may be discon nected wired incorrectly or incompatible with the controller Check that the probe is connected and wired properly Verify that the probe is of the correct type for which the controller was configured to use If the probe is not correct use the correct probe The controller controls or attempts to control at an inaccurate temperature Check that the calibration parameters are all correct according to the certifica tion sheet If not reprogram the constants The memory backup battery may be weak causin
63. t assiettes set ave TT 4 1 Unpacking s 5 44 eae ee qu Cee RR EA S 11 4 2 InstallatlOn oca a a ee rev cames 11 4 2 1 SUD a eser done xem wem a A a eae s 11 4 2 2 Heater Stirter LN Cooling 2 4 uae do Yom ara Ro uomo Aa E au 11 ALAI Heater Comnectton s ue oo GG ue eub AGL Mie jaune due pr a ak espe pde 11 422 2 St rMotorConnection s s s 2 24 eco voce RR RR eS a aa 13 4224 ENGCODIGUO x24 etre ke stum ese Nol ita ap add die 13 4 2 3 Control Probes 64 44 8 jbo maras da Euepe XE RES 14 4 2 4 Thermocouple Prob xr dde RR dE de al dd 14 4 2 5 POWGE 3 tai oed Tt aros cede qun de did ha we Re Mae de d 14 4 2 6 FUSES 1 256 de do on d deu de d de d de do dob ded ess m e de pe od de dox 14 42 7 Power Cord 0 6 8 ae yale CRS ab SPERG Sx x ERI SU 15 4 3 Setting the Temperature 15 5 Parts and Controls 17 5 1 Front Panel s sss oia io ta ne a DAS Le 17 5 2 Back Panel cs 23m RR R4 v 4 a e 646448 18 6 General Operation 21 6 1 Control System d ko sages sa esp X das e 21 6 2 Power eae See om ia dot ee d gh s 21 6 3 Heder i a et o Ee bow y de awe eR RU S P xs 21 64 ILNGCoolung ido nce Rom hem de d s Sa EE 22 6 5 Temperature Controller 22 ii 7 Controller Operation 23 7 1 Process Temperature 23 3 2 ResetCut out 23 7 3 Temperature Se
64. t point 25 7 3 1 Programmable Set points 25 7 3 2 Setpoint Value doy Gece A den te em Aie re de aa ct 25 7 3 3 Setpoint Vernier lt a s Gye ere e He Wed ee dde ds 26 7 4 Temperature Scale Unit 2 13 SCA ei a 4868 eee RSG uc E X WU EG 27 7 51 Scan Control vos 2 EXE EX Del E Rx HEELS Eye 28 7 52 Scan Rates seve tbe wk e eG Y wok hoy wo Re y ROG e Re E UR 28 7 06 Ramp and Soak Program 28 7 6 1 Number of Program Set points 29 7 6 2 Mou 25 5 Le ur dE T Ne a A 29 7 6 3 Program Soak TIMES ai RA A Ux 30 7 6 4 Program Function Mode eco neru due a aa a a 30 7 6 5 Program Control a De ds 31 7 7 Secondary MENU eee n x a US E RON a 31 7 8 Heater Power cc c 444 48 688 4 da me o bu se 31 7 9 Proportional Band 32 TIO COURS PCI c r 33 7 11 Controller Configuration 34 7 12 Probe Parameters RTD Sensor 34 7 12 1 RS esi epeen ae aida 35 7 2 2 ALPHA i 34 4 ly ee Ges a dar e 5345 35 7 13 Operating Parameters 35 TAZA Cutout Reset Mode soii AN wa we oa ew e dd ead s 35 7 13 2 Soak Stability osc 440 0845484 00 PES ee G45 FSGS BS 36 7 13 3 Boost Temperature Offset os ss sse e wR RAE oe sente 36 7 14 Serial Interface Parameters 36 7 14 1 Baud Roe cocida de A xeu xa eR x E Pe s 36 7 14 2 Samp
65. ter nates with the heater power to maintain a constant temperature The LN cooling cable is fed through the strain relief in the back panel and the spade connectors are attached to the appropriate terminals on the internal terminal block See Figure 3 The control probe connector for the system attaches the 100Q control RTD 19 6 General Operation Control System 6 1 6 2 6 3 General Operation Control System The 7900 temperature controller is specified for use with the Rosemount de signed calibration baths The controller s flexibility enables it to be used with all Rosemount designed calibration bath systems It is the responsibility of the user to ensure that the components are chosen and the system constructed to ensure safe and proper operation of the complete sys tem The user should have a good knowledge of and experience with electrical fundamentals and wiring practices as well as control systems Hart Scientific cannot be responsible for any damages or injuries resulting from improper de sign or operation of the control system Technical support for setting up and operating a control system using the 7900 controller is available by telephone or fax from Hart Scientific Be sure to read this 7900 user manual completely Power Power to the controller is provided by an AC mains supply as specified in Sec tion 3 1 Specifications Power to the controller passes through an internal filter to prevent switching s
66. ter used must be able to measure the temperature with higher ac curacy than the desired accuracy of the system RTD Probe Calibration Calibration Points In calibrating the controller Ry and ALPHA are adjusted to minimize the set point error at each of two different temperatures Any two reasonably sepa rated temperatures may be used for the calibration however best results will be obtained when using temperatures which are just within the most useful operat ing range of the system The further apart the calibration temperatures the larger will be the calibrated temperature range but the calibration error will also be greater over the range For instance if 50 C and 150 C are chosen as the calibration temperatures the controller may achieve an accuracy of say 0 03 C over the range 40 to 160 C Choosing 80 C and 120 C may allow the controller to have a better accuracy of maybe 0 01 C over the range 75 to 125 C but outside that range the accuracy may be only 0 05 C Measuring the Set point Error The first step in the calibration procedure is to measure the temperature errors including sign at the two calibration temperatures First set the temperature to the lower set point which we will call tj Wait for the system to reach the set point and allow 15 minutes to stabilize at that temperature Check the stabil ity with the thermometer When both the system and the thermometer have sta bilized measure the system temperature with
67. terface DOWN Ce radon lt lt Menu SET SET SET 2 ser X 5 y Y 2 Y Cut out BAUD m et Mode C me GIO SET EXIT SET EXIT SET EXIT w ser EXIT a Adjust 4 SET EXIT SET EXIT SET EXIT E SET EXIT E s im Sample ALPHA e Stability Period M co SET EXIT SET LH EXIT SET EXIT A SET EXIT E Tem I z SETIEXIT SETIEXIT SET EXIT lt seven ES Boost Duplex ca oos Mode 5 SET Exit gt SET EXIT ser EXIT 8 Adjust Adj Duplex SETEXIT SET EXIT SET EXIT RR Y SET EXT gt al Er Figure 6 Controller Flow Chart 24 just Linefeed SET EXIT Eo j Adjust H SETEXIT Y t a g T T SET EXIT SET EXIT gt WU SETIEXIT n 7 Controller Operation Temperature Set point 7 3 7 3 1 7 3 2 SET Reset cut out This action also switches the display to the set temperature function To return to displaying the temperature press the EXIT button If the cut out is still in the over temperature fault condition the display will continue to flash cut out The bath temperature must drop a few degrees below the cut out set point before the cut out can be reset Temperature Set point The temperature can be set to any value within the range given in the specifica tions The operator must know the temperature range of the particul
68. the power entry module of the in strument mark the instrument so the user can visibly see the fuse size and rat 4 Quick Start Setting the Temperature 4 2 7 4 3 ing for fuse replacement Be sure to change both fuses to the new rating and correct characteristic The controller uses 0 2 amps of current This current should be taken into con sideration when calculating the system power Example when using the power of the system P z Power of the system Total Watts V z Nominal line voltage 115 VAC I Fuse current P 0 9x v I 125x Example when using the system current I System current I Fuse current rating I 125x1 Power Cord Once the correct fuse is selected the proper power cord can be selected The controller is shipped with a 20 Amp 125 VAC power cord to accommodate the maximum power rating An extra power cord rated for 15 Amps 125 VAC is in cluded If the total system current is 12 Amps or less the 20 Amp power cord may be replaced with the 15 Amp power cord If the system current exceeds12 amps using the 15 amp power cord the recommendations of the National Elec tric Code NEC are exceeded You must use the 20 amp power cord once the system current exceeds 12 amps WARNING DO NOT USE THE 15 AMP POWER CORD UNDER ANY CIRCUMSTANCES IF THE SYSTEM CURRENT EXCEEDS 12 AMPS Setting the Temperature In the following discussion and throughout this manual a solid box around the word SET U
69. units C or E at the left c 40 00 Set point 4 value in C If the set point value does not need to be changed then press EXIT to resume displaying the temperature To adjust the set point value press UP or DOWN Increment display C 42 50 New set point value When the desired set point value is reached press SET to accept the new value and access the set point vernier If EXIT is pressed any changes made to the set point are ignored SET Accept new set point value Set point Vernier The set point value can be set with a resolution of 0 01 C The user may want to adjust the set point slightly to achieve a more precise temperature The set point vernier allows one to adjust the temperature below or above the set point by a small amount with very high resolution Each of the 8 stored set points has an associated vernier setting The vernier is accessed from the set point by pressing SET The vernier setting is displayed as a 6 digit num ber with five digits after the decimal point This is a temperature offset in de grees of the selected units C or F 0 00000 Current vernier value in C To adjust the vernier press UP or DOWN Unlike most functions the ver nier setting has immediate effect as it is adjusted allowing the user to continu ally adjust the system temperature with the vernier as the temperature is displayed SET does not need to be pressed Increment display
70. user selected The heater power switch is used to select the appropriate heater power levels for heating and con trolling at various temperatures Selecting HIGH heat manually overrides the automatic system 6 The cooling power switch controls power to the LN cooling Once the LN cooling is energized the flow is automatically controlled Back Panel The following features are found on the back panel see Figure 5 of the con troller 1 the cut out thermocouple connector TC 2 the RS 232 interface connector 3 the IEEE 488 GPIB interface connector 4 the power cord 5 the heater connector 6 the stirrer motor connector 7 the LN cooling connector and 8 the control probe connector 1 The thermocouple cut out probe senses the system temperature for the safety cut out When the temperature exceeds the cut out set point open ing a relay inside the controller disables the heater The thermocouple probe is Type K 2 The RS 232 communications cable is connected to this 9 pin DB sub miniature connector This enables the controller to be programmed and operated remotely 3 The IEEE 488 GPIB interface connector is for remote computer control 4 The power cord is rated at 115 VAC at 20 amps CAUTION Do not draw more than 20 amps Note The heater and system fuses are internal a HEATER STIR MOTOR 0 AMP MAX cx T i PROBE e m D A POWER 115V AC 60 Hz M FUSE INT
71. ver the set point is 3 C higher than the actual temperature To override this function so that the heaters stay on high heat for higher temperatures use the F1 command To control the heater with the digital interface the front panel heater switch must be set to LOW The heater function is controlled with the F1 command Setting the FI parameter to 0 sets the heater to LOW and setting the param eter to 1 sets the heater to HIGH Sending FI with no value returns the cur rent state of the heater control When the heater setting is changed the heater relay can be heard as it opens or closes Cooling Control To enable the cooling device with the digital interface the cooling switch on the front panel must be off The cooling power function is controlled with the F2 command Setting the F2 parameter to O turns the cooling off and setting 8 Digital Communication Interface Power Control Functions Table 3 Serial Interface Commands Command Command Returned Acceptable Command Description Format Example Returned Example Values Display Temperature Read current set point s etpoint S set 9999 99 C or F set 150 00 C Set current set point to n s etpoint n s 450 Instrument Range Read vernier v ernier V v 9 99999 v 0 00000 Set vernier v ernier n v 0 0001 Depends on configuration Set temperature units u nits c f CorF
72. witch 1 The digital display is an important part of the temperature controller be cause it not only displays set and actual temperatures but also displays various functions settings and constants The display shows temperatures in values ac cording to the selected scale units C or F 2 The control buttons SET DOWN UP and EXIT are used to set the tem perature set point access and set other operating parameters and access and set calibration parameters A brief description of the button functions follows SET Used to display the next parameter in a menu and to set parameters to the displayed value DOWN Used to decrement the displayed value of parameters UP Used to increment the displayed value EXIT Used to exit from a menu When EXIT is pressed any changes made to the displayed value will be ignored 3 The on off switch controls power to the instrument It powers the stirring motor the controller heater circuit and LN cooling 4 The control indicator is a two color light emitting diode This indicator lets the user visually see the ratio of heating to cooling When the indicator is red the heater is on When the indicator is green the heater is off and the controller is cooling 7900 TEMPERATURE CONTROLLER Hart Scientific HEATING COOLING DEAE 4 Figure 4 Front Control Panel 17 7900 Temperature Controller User s Guide 5 2 5 The heater power is either automatic or
73. zed for more than 10 days the instrument needs to be energized for a dry out period of 2 hours be fore it can be assumed to meet all of the safety requirements of the IEC 61010 1 If the product is wet or has been in a wet environment take nec essary measures to remove moisture prior to applying power such as storage in a low humidity temperature chamber operating at 50 C for 4 hours or more The instrument is intended for indoor use only The instrument is a precision instrument Although it has been designed for op timum durability and trouble free operation it must be handled with care Operate the instrument in room temperatures listed in Section 3 2 Environmen tal Conditions The instrument is vented and clearance of 3 inches 7 62 cm is recommended above and around the sides the instrument DO NOT remove the feet attached to the bottom of the instrument If the feet are removed contact an Authorized Service Center for replacements DO NOT place the instrument on top of a calibration bath or dry well where it would be in contact or direct path of heat DO NOT stack items on top of the instrument BURN HAZARD The instrument can be used to control instruments which generate extreme tem peratures Precautions must be taken to prevent personal injury or damage to objects Probes may be extremely hot or cold when removed from a calibration bath Cautiously handle probes to prevent personal injury Carefully place probe

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