Omega Engineering CL521 User's Manual
Contents
1. Calibration Figure 7 7 Millivolt Calibration Using the CL521 27 As in thermocouple calibration loading of the calibration signal is indicated by an increase in the signal stabilization time At 110 mV the CL521 can supply a current of about 0 3 mA SECTION 8 RS 232C OPTION 8 1 GENERAL DESCRIPTION The RS 232C Option includes Digital input output and Analog output Digital input output Serial I O compatible with RS 232 C For remote control by computer or interfacing to a printer Selectable transmission rate 150 600 baud Isolated from the measurement Analog output Voltage proportional to the display reading in measurement mode During normal operation 1 mV of analog output voltage corresponds to 1 degree 0 1 mV or 0 1 ohm of the display reading Output voltage is multiplied by 10 when deviation measurement is selected Output is isolated from the measurement circuits Accuracy 0 296 rdg 1 degree 0 1 mV or 0 1 ohm in normal measurement 0 296 rdg 0 1 degree 0 01 mV or 0 01 ohm in deviation measurement 8 2 INSTALLING THE RS 232C DIGITAL INTERFACE OPTION If you are field installing your option follow this procedure Before installing the option disconnect the AC Power Adaptor and switch the CL521 off by pressing the OFF key Next remove the four screws at the bottom of the unit and carefully lift the rear of the upper cover and remove the cover Remove the dummy plate at the rear o2. Figure 5 2 Connecting a 4 Wire Resistance Probe to the CL521 15 In three wire connections one wire is connected to one end of the resistance probe and two wires are connected to the other end Probe resistance can be measured using many different methods but all of these require that at least two of the conductors in the cable are identical Some methods even require that conductor resistances be tuned to specific constant values The voltage across the probe can also be measured with three wires The voltage drop in the current circuit is measured and cable effects are compensated for on the assumption that the voltage drop in the feed conductor is identical to that in the return conductor IR Constant current co R E 4 9 Er R E2xEmg I IR Figure 5 3 Pt100 Measuring Circuit if the probe is connected to the CL521 using three conductors the instrument automatically detects the lack of the fourth conductor and begins to operate in the three wire mode The fourth conductor should however be used whenever possible 4 Pt100 Figure 5 4 Connecting a 3 Wire Resistance Probe to the CL521 16 In actual bridge circuit measurements the probe is often connected using four leads two of which are connected across the sensing probe while the other two are shorted to form a compensation loop If the cable leads and connections are correct the resi
3. 00s eee eens 21 TABLE OF CONTENTS Continued SECTION PAGE SECTION 7 THERMOCOUPLE SIMULATION AND MILLIVOLT CALIBRATION oven xe ex es eee dre te Se Reds 21 7 1 Principle of Thermocouple Simulation llle 21 7 2 Thermocouple Simulation 0 leeren 21 7 2 1 Connection and Selection of Compensation Modes 21 Fee Simulation s See Seng 4 waar ead ea Saee Matas CR CI 24 Ee Electot Loadihg aude eee Seale og ET RO SLA AE WE nas 26 7 3 Millivolt Calibration 3 ics u i Gag Rieu YO Bare Ree AD AOV SCR Den 27 SECTION 8 RS 232C AND ANALOG OUTPUT OPTION 28 8 1 General Description amp vao gk Sta koe a Ao eee SOE RE Ra ESOS 28 8 2 Installing the RS 232C Digital Interface Option 00 28 8 2 1 Data Format and Baud Rate 2 ee ee 29 8 2 2 Connection Gables 2s uoc ods eh cow anes EE ee a 29 8 2 3 Output Message Format and Timing 22H 31 8 2 4 End Characters of the Output Message lee ee eee 32 8 2 5 Remote Control by Computer 2 llle ees 32 8 3 Analog Output 45 225 2s 4 8 cer d ESSA ente a C ese eo BN 35 8 3 1 Analog Output Specifications 2e 36 SECTION 9 SERVICE AND CALIBRATION 000 eee 36 SECTION 10 SPECIFICATIONS 0 0 0 0 cece ee ee ees 38 ii SECTION 1 INTRODUCTION 1 1 GENERAL DESCRIPTION The OMEGA CL521 is a precision high accuracy calibrator for use on the bench or in the field Featuring exceptionally high accura
4. non condensing STORAGE TEMPERATURE RANGE 4 to 140 F 20 to 60 C POWER 110 220 Vac 50 60 Hz POWER CONSUMPTION 3 VA max BATTERY POWER NiCad 90 h between recharging 10 h for CL521D low battery indication standard RECHARGE TIME 12 hours 20 hours if unit is used during recharging DIMENSIONS 4 H x 7 3 W x 9 D 102 x 185 x 229 mm WEIGHT 4 Ibs 1 8 kg 38 RANGES LINEARITY AND RESOLUTION Linearity Resolution Standard Range C error C C IEC 584 1 210 to 200 0 2 ASTM E230 200 to 1200 0 1 Sensor Type and Material J Fe CuNi Fe Const 0 1 0 1 0 5 K IEC 584 1 255 t 220 0 2 NiCr NiAl ASTM E230 220 to 140 0 2 0 2 Chromega DIN 43710 140 to 1372 0 1 0 1 Alomega T IEC 584 1 255 to 230 Cu CuNi ASTM E230 230 to 160 Cu Const 160 to 400 oo ooo A E a auk oo ooo noo ana e E IEC 584 1 260 to 250 NiCr CuNi ASTM E230 250 to 220 Chromega Const 220 to 1000 R IEC 584 1 50to 250 0 1 Pt13 Rh Pt ASTM E230 250 to 1768 0 1 IEC 584 1 50to 600 ASTM E230 600 to 1760 DIN 43710 IEC 584 1 400 to 1200 Pt30 Rh Pt6 Rh ASTM E230 1200 to 1820 NBS Mono 0 to 1300 Nicrosil Nisit graph 161 Fe CuNi DIN DIN 43710 200 to 900 0 2 Fe Const Cu CuNi DIN DIN 43710 200 to 600 0 2 Cu Const DIN 43760 200 to 200 0 05 200 to 1200 0 05 10 to 110 mV 0 002 mV ohm 0 to 400 ohm
5. C Thermocouple type selection TO Type E Chromega Const Ti Type R Pti3 Rh Pt T2 Type S Pt109cRh Pt T3 Type B Pt30 Rh Pt6 Rh T4 Type N Nicrosil Nisil T5 Type T Cu CuNi ASTM T6 Type K Chromega Alomega NiCr NiAI T7 Type J Fe CuNi ASTM T8 Type TD Cu CuNi DIN T9 Type JD Fe CuNi DIN 32 D Entering Calibration Values V reading The first character of the value may be a digit or a space Only the first five digits of the reading are recognized V command examples 100 00 V 100 00 V 100 00 V 5 V1234 5 E Triggering the Digital Output After the CL521 is switched ON it starts to put out messages at the digital output The time interval between messages is determined by memory Register 7 The automatic output is meant to be used with a printer P1 Disables the automatic output and requests one output message The requested output message is sent after this command PO Re enables the automatic output The first output message is sent just after this command and the following messages with the time interval determined by the memory in Register 7 F Setting the End Characters of the Digital Output After the CL521 is switched ON all output messages are followed by the codes CR ODH and NUL 00H if the printer cannot feed the paper with this end character combination the end characters can be changed with computer command Y The new end characters set by the computer are used until the CL521 is swi
6. 8 and one stop bit 1 the device timeout is not checked CSO DSO CDO OPEN COM1 600 N 8 1 CS0 DSO CDO BIN FOR RANDOM AS 1 Fills input buffer with spaces L SPACE 20 Send P1 message to the CL521 P1 causes output of one message and disables the automatic output The input line should be cleared before continuing the program execution If there is extra characters on the line it would disturb the program execution later PRINT 1 P1 WHILE LOC 1 gt 0 L INPUT 1 1 WEND The thermocouple measurement with TC type K is selected and one output message requested The keypad operations are allowed PRINT 1 F1T6P1FO Wait until the entire message is on the line WHILE LOC 1 lt 20 WEND Read the message from the line L INPUT 20 1 Check of M C switch position IF LEFT L 1 M THEN 90 INPUT Turn the M C switch to MEASUREMENT and press RETURN A CLS GOTO 40 Check of meas unit IF MID L 18 1 C THEN 120 INPUT Select Celsius as the meas unit and press RETURN A CLS GOTO 40 Check of connections CLS INPUT Check the wiring and CJ mode and press RETURN A CLS Program heading on the screen PRINT TRACKING OF TEMPERATURE CHANGES 35 1 Make sure that the initial reading is printed 140 START t XT 0 Request and receive of an input message from the CL521 150 PRINT 1 P1FO 155 WHILE LOC 1 20 158 WEND 160 L INPUT 20 1 Get the
7. Output to the serial interface of the CL521 can be stopped by connecting Pin 5 of the connector to a negative voltage During normal operation Pin 5 must be kept positive This can be easily done by connecting it to Pins 4 or 20 Pins 4 and 20 are internally connected to a positive voltage 29 Printers are normally wired as RS 232C DTE devices and computers as DCE devices Suitable cables for standard computers and printers are illustrated in Figures 8 3 and 8 4 wires drawn with dotted lines may not be needed in all devices Some microcomputers are wired as DTE devices The cable of Figure 8 4 with one additional wire from the computer connector Pin 2 to the CL521 connector Pin 3 can normally be used in those cases Check the instruction manual of your printer or computer to find the suitable cable connection CL521 computer gt FeNnD y T amp D FoND lt lt TxD 2 lt RxD 3 3 RyD RTS XK rb gt gt RTS cts 2 cts psr i4 55 DSR SGND 5 s GND Lp gt gt 20 DTR CL521 printer Feno 1 lt gt FGND T 0 X gt 1x0 RxD 2K gt R D RTS RTS cts pP 3 cts 0SR lt lt rb gt gt amp psR SGND L senp co 3 co DTR 2 lt La 5 DTR Figure 8 4 Connection Cable for a Printer 30 8 2 3 Output Message Format and Timing After switching the CL521 on it starts to send messages to the digital
8. at the left side of the display Deviation measurements can be used for example to investigate the behavior of temperature controllers thermostats The deviation function comparison value is zeroed whenever the CL521 is switched on To check or set this value proceed as follows 20 Set the MEASUREMENT CALIBRATION switch to the CALIBRATION position To recall the comparison value contents of Register 8 enter RCL 8 To set a new comparison value for example 20 0 enter 20 0 STO 8 After checking and or setting the comparison value remember to return the MEASUREMENT CALIBRATION switch back to the MEASUREMENT position 6 4 CHECKING MINIMUM AND MAXIMUM READINGS The CL521 stores the minimum and maximum values shown on the display starting from the time it is switched on The minimum and maximum values can be recalled by pressing the MIN or MAX keys respectively The MIN and MAX functions are indicated by the letters L low and H high at the left edge of the display The values are reset to the current display value when the RESET key is pressed or a new main function is selected 6 5 RETURNING TO NORMAL MEASUREMENT MODE To return to the normal measurement mode from another measurement function press the NORM key SECTION 7 THERMOCOUPLE SIMULATION AND MILLIVOLT CALIBRATION i 7 1 PRINCIPLE OF THERMOCOUPLE SIMULATION Thermocouple simulation refers to the process of replacing a thermocouple with a device which mimic
9. CL521 Temperature Calibrator Thermometer ito E Xs Operator s Manual M1269 0491 e OMEGA An OMEGA Technologies Company OMEGA warrants this unit to be free of defects in materials and workmanship and to give satisfactory service for a period of 25 months from date of purchase OMEGA Warranty adds an additional one 1 month grace period to the normal two 2 year product warranty to cover handling and shipping time This ensures that our customers receive maximum coverage on each product If the unit should malfunction it must be returned to the factory for evaluation Our Customer Service Department will issue an Authorized Return AR number immediately upon phone or written request Upon examination by OMEGA if the unit is found to be defective it will be repaired or replaced at no charge However this WARRANTY is VOID if the unit shows evidence of having been tampered with or shows evidence of being damaged as a result of excessive corrosion or current heat moisture or vibration improper specification misapplication misuse or other operating conditions outside of OMEGA s control Components which wear or which are damaged by misuse are not warranted These include contact points fuses and triacs There are no warranties except as stated herein There are no other warranties expressed or implied including but not limited to the implied warranties of merchantability and of fitness for a particular purpos
10. E A UE Ee 2 2 2 Removing the Carrying Case ee es 2 2 3 Charging the Battery ee ens 3 2 4 Wiring Connections lle ee eas 3 SECTION 3 GENERAL OPERATION leen 4 3 1 Front Panel Functions ccce ee htt ns 4 3 2 Initial Start up oo is 5 555 0 6 recess UR Roe og dub e va De ean 6 SECTION 4 THERMOCOUPLE AND MILLIVOLT MEASUREMENTS 6 4 1 Theory Of Operation dones Oe IR RC s ds 6 6 4 2 Reference UNCON 2 uui ne qoo yeso Eee wale ce OD ae o aues 7 4 3 Thermocouple Measurements 0 1 ce nnn 8 4 3 1 Connections and Reference Junction Mode Selection 8 4 3 2 Measuring Temperature 2 hn 11 4 3 3 Checking or Changing Reference Junction Temperature 12 4 4 Measuring Thermocouple Resistance 2 0 eee ee ee eee 13 4 5 Measuring Millivolts 0 ee ee eee 14 SECTION 5 Pt100 AND RESISTANCE MEASUREMENTS 14 5 1 General Information 2 eee ee es 14 5 2 Connecting a Resistance Probe tothe CL521 0 2 0 020 0s 15 5 3 Pti00 Temperature Measurement 0 0 0 0 ee eee eee 17 5 4 Resistance Measurement llle 19 SECTION 6 ADDITIONAL MEASUREMENT FUNCTIONS 20 6 1 Using Other Measurement Functions 0 0 0 ee ee eee 20 6 2 Monitoring Rate of Change 2 ee ns 20 6 3 Indications of Deviation et ene 20 6 4 Checking Minimum and Maximum Readings lees 21 6 5 Returning to Normal Measurement Mode
11. measure value from the reading 170 T VAL MID L 10 8 if the temperature is changed 1 2 degrees or more the time and the temperature is printed 180 IF ABS T XT 5 AND START 0 THEN GOTO 150 190 LPRINT TIME USING C T 200 XT T START 0 Next measurement 210 GOTO 150 The RS232 cable connection between the CL521 and 25 pins IBM PC computer CL521 IBM PC pin pin 2 35 3 3 lt 2 5 E Ser wt 20 The RS232 cable connection between CL521 and 9 pins IBM AT computer CL521 IBM AT pin pin 2 5 2 3 3 5 eas 20 35 2 8 3 ANALOG OUTPUT The analog output is intended to be used for connecting a recorder The output is isolated from the measurement circuits by means of optocouplers and a DC DC converter The electronics needed for the output is placed on the same board as the CL521 RS232C Option The output voltage is 1 mV 1 degree of the reading and 10 mV 1 ohm or 1 mV of the reading When measuring the deviation from the preset value DIFF function the normal output voltage is multiplied by 10 The output voltage is limited to the range 595 to 3500 mV 8 3 1 Analog Output Specifications Normal measurement Display reading Output voltage 255 to 2370 C 255 to 2370 mV 418 to 3500 F 418 to 3500 mV 10 0 to 110 0 mV 100 to 1100 mV 0 to 350 0 ohms 0 to 3500 mV Deviation measurement Display reading Output voltage 59
12. necessary conductor lead resistance is marked on the indicating device When checking such devices an equivalent resistance must be included in the circuit Analog Meter Figure 7 5 Calibrating an Analog Meter with the CL521 When part of the original wiring is included in the circuit that is being checked the added resistor must be adjustable The wire resistance should be set to the required value by shorting the indicating device and using the TC Q measurement on the CL521 26 Original Short circuit Tune with this tuning trimmer the device Resistance of the circuit Analog Meter Part of the original circuit p Select TCohm re HE c f cl 3 3 3 FE Gee C C5 E Measurement Figure 7 6 Calibrating an Analog Meter with the CL521 NOTE The indicating device may be damaged if its connections are not shorted during measurement 7 3 MILLIVOLT CALIBRATION In thermometer calibration the user enters the required temperature values and the CL521 provides the corresponding millivoltage to the TC and mV terminals Millivolt values can also be entered directly as millivolts for output at the terminals The available range from the CL521 is 10 to 110 mV To switch from thermocouple calibration to millivolt calibration or vice versa simply press the TC mV key once Calibration 10 4110mV value CJ MODE MAN
13. output The length of a message is 18 characters and the time interval between two messages is initially set to 12 seconds When needed the time interval may be changed by storing the new time interval in seconds in memory Register 7 Register 7 also controls the timing of the calibration value step function Any value from 5 to 1000 seconds can be stored To set the time interval of one minute 60 seconds Set the MEASUREMENT CALIBRATION switch to the CALIBRATION position Keyin 60 STO 7 The output message string consists of the following parts Char 1 Main function M Measurement C Calibration Chars 3 4 Sensor type E Chromega Const R Pt138 Rh Pt S PtlO Rh Pt B Pt80 Rh Pt6 Rh N Nicrosil Nisil T Cu CuNi ASTM K Chromega Alomega NiCr NiAl J Fe CuNi ASTM TD Cu CuNi DIN JD Fe CuNi DIN P Pt100 Chars 6 8 Special function MIN Minimum reading MAX Maximum reading RAT Rate of change of the measurement TCR Thermocouple resistance measurement DIF Deviation measurement Chars 10 17 Reading The first character of the reading is or the digits follow after the sign The format of the reading is the same as in the display Char 18 Meas unit C C F F R ohm space mV Print out examples MP RAT 1000 0 C C JD 0 1 C MK 4666 6 F MP MIN 15 00 C MJ 9 990 31 8 2 4 End Characters of the Output Message After sending the message string the CL521 always
14. the device with copper conductors Compensation is not necessary since no thermoelectric potentials are present in the circuit This method eliminates errors resulting from reference junction compensation and thus the functioning of the device itself is tested In this case the operation of the reference junction compensator must be tested separately Cu To device being checked Simulation temperature Reference junction temperature simulation value in register 9 CJ MODE z MAN Figure 7 3 Manual Reference Junction Compensation with the CL521 23 If the measuring device is intended for use so that the reference junction temperature is controlled at some temperature other than 0 C this temperature must be entered into Register 9 in C For example to enter 50 C into Register 9 enter 50 STO 9 7 2 2 Simulation Turn on the CL521 by pressing the ON key If the CL521 was most recently used to perform a similar simulation it is ready to use once the power is switched on If it has not recently been used for simulation Check that the MEASUREMENT CALIBRATION switch is in the CALIBRATION position If thermocouple measurement is selected the display indicates a value of 0 If the arrow at the top of the display indicates Pt100 press the ENT key The CL521 changes automatically to thermocouple measurement and displays a value of 0 If the displayed value is in millivolts the arrow at the right edge of the
15. 5 to 350 0 C 595 to 3500 mV 59 5 to 350 0 F 595 to 3500 mV 5 95 to 35 00 mV 595 to 3500 mV 5 95 to 35 00 ohms 595 to 3500 mV SECTION 9 SERVICE AND CALIBRATION CL521 does not need any regular service except for calibration checks In case the unit is not functioning properly we suggest you contact OMEGA since troubleshooting of microprocessor based circuits can be very difficult without a thorough knowledge of both the hardware and software of the unit We suggest the calibration of the CL521 is checked approximately six months after delivery The proper calibration period after that is one year To check the calibration of the unit the four screws at the bottom of the unit must be removed To remove the top cover the rear of it must first be carefully lifted When the cover is removed the calibration can be done easier by removing the screws at the front and back of the terminal panel and lifting the panel aside Calibration is performed with the CL521 in battery operation disconnected from the AC Power Adaptor Switch the unit on for about ten minutes before performing the calibration procedure 36 The following equipment is needed for calibration Voltage standard voltage 50 to 110 mV error less than 5 uV Resistance standard resistance 100 to 400 ohms error less than 20 mohm K type thermocouple probe Ice bath or OMEGA TRCIII Ice Point Reference Chamber Calibration is rather different because of the so
16. 938 1591 en 8 uongJqia3 iuepuedepu 9 s 1uepuedepur pasn aq osje KgjN indino peddejs pewozne uj pese yo Jasn ayy q pebugeuo pue pejje2s eq Aew uoju 193sjbe1 Arowaw 994j ue SayBJodsooUy 2610 9uL EARE nS Ls Dou tg 19391621 wou pej Boae1 anjea saque 63 kJowew WOJ NJBA UOTBIGHeo 8 829 j s 2 26 en e saque 63 en BA uopjeJqqeo e 193u3 tou ty 49 sja jo 3uequoo j 809J 53 191 si601 AJowew wos en BA pesay 39 1939 D9J ul Z aces 63 1938169J Agowew uj en BA 91075 Ke dsip J881 suojjound jeued 1uo44 squaw eunseew e dnooouileui Suranp quaweinssaw 92u83 9J ejdnooou9u DL 1ueuJgJnsgeuU 3 OA Himu pue ajdnosowseyy AWPL quew 9Jns89u VOUBISISeY VG eqoud O0T1d 8 Guysn quew eJnsBeu eJniBJeduJS Q0Tid 3OOW IN3W3HWOSY3IW sBuyzaqua Aq poeiij81S YG Je319 DboJ Azowew u pelois sen JBA jO yndqjno peddeis oneujoiny L g anfa sabusyo eubis snonumuoa2 sesneo puo2es OM J9A0 Dujssalg NJEA 38s esmejoep essei1ou pus squaweinsesw e dnoaou Jequi uj 10329 o epu jodows y exmeJeduje yame AW OL yun Woweseinsesw eJni8Jed wu91 oui s12e oS u21 3o 2o epour yuawesn SBE ewou 0 UJn193 tWYON anjea ejdsip quasina 03 son BA XVIA pue NIW 198934 113531 Bujpeas wnuyxew Kejdsig x vi Bujpee1 uuu Ke dsig NIW g 193 boJ Arowaw ul P91038 enjBA WOW uOp3BI
17. A pe3eede 3QOW CD ssaJg NOILONNC 3O9N3H333H JINODOWY3SHL adAq ajdnosow Jey paJinboa y sajeajpur doi 38 Mose 34 Iun Ajpayeedas 3dAL DL 5919 3dAl 31IdNODOWY3SHL 3 2 INITIAL START UP The CL521 is switched on and off by pressing the ON and OFF keys respectively After the instrument is switched on it performs various routines and self tests A message flashes on the display indicating the version of the CL521 After this the unit begins operation in the most recently used mode of operation SECTION 4 THERMOCOUPLE AND MILLIVOLT MEASUREMENTS 4 1 THEORY OF OPERATION A thermocouple is a temperature probe composed of two wires of different materials connected together There is a specific thermopotential between the wires which varies non linearly as a function of temperature If two wires of different materials A and B are connected in a loop as shown the thermoelectric effect causes a flow of current through the loop corresponding to the temperatures T1 and T2 at the junction points Ti 1 T2 B Figure 4 1 Basic Thermocouple Circuit if the circuit is broken its thermopotential can be measured Assuming the voltmeter does not create a load in the circuit the potential is determined solely by temperatures T1 and T2 the thermopotentials of the copper wires and the thermocouple conductors cancel each other as long as both connections are at the same temperature Figure 4 2 Thermocouple Circult with Meter N
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19. ANTY REPAIRS OR CALIBRATION following information available BEFORE contacting consult OMEGA for current repair calibration charges OMEGA Have the following information available BEFORE 1 P O number under which the product contacting OMEGA was PURCHASED 1 Your P O number to cover the COST of 2 Model and serial number of the product the repair calibration under warranty and 2 Model and serial number of product 3 Repair instructions and or specific 3 Repair instructions and or specific problems you are having with the problems you are having with the product product OMEGA s policy is to make running changes not model changes whenever an improvement is possible That way our customers get the latest in technology and engineering OMEGA is a registered trademark of OMEGA ENGINEERING INC Copyright 1991 OMEGA ENGINEERING INC All rights reserved including illustrations Nothing in this manual may be reproduced in any manner either wholly or in part for any purpose whatsoever without written permission from OMEGA ENGINEERING INC Printed in Finland TABLE OF CONTENTS CL521 TEMPERATURE CALIBRATOR THERMOMETER SECTION PAGE SECTION 1 INTRODUCTION 0 llle hh hn n 1 1 1 General Description 2 be ee ee ee ee ns 1 TZ FOROS ooo ru or Were Saves EUR UR UE E ES Sle eed es 1 1 3 Available Models 0 0 ee ee ee ee 1 SECTION 2 INSTALLATION 0 cee eee eee eee 2 24 Unpacking go ux UU o eae ei y RC EE
20. CL521 to measure the voltage across the resistor and check that the reading is 0 mV 0 01 mV Adjust the analog output to zero by using the trimmer ZERO on the option card Use a DVM that reads to four places Then switch the CL521 to TCQ measurement and check the display reading The display digit representing tenths of milliohms should be less than four to make sure that there will be no trouble with rounding Find a proper reading for example by connecting extra test leads in series with the resistor If the resistance reading is for example 312 33 ohms adjust the analog output to 3123 mV by using the trimmer SPAN on the option card Repeat the ZERO and SPAN adjustments until both adjustments are within specification The CL521 is now recalibrated Reassemble the unit and install the cover 37 SECTION 10 SPECIFICATIONS DISPLAY 6 digit LCD 0 41 10 4 mm OVERRANGE INDICATION Display blinks max reading of selected range READING RATE 1 25 to 2 5 readings per second WARM UP TIME lt 1 min INPUT IMPEDANCE gt 100 Mohm NMRR gt 60 dB 50 60 Hz CMRR gt 140 dB 50 60 Hz with 1 k ohm imbalance OVERVOLTAGE PROTECTION Inputs protected up to 110 Vac RMS or de ACCURACY 0 02 rdg 6 mV thermocouple and mV 0 02 rdg 0 04 ohms RTD and Resistance COLD JUNCTION COMPENSATION ERROR 0 2 C at 23 C 0 01 C C TEMPERATURE COEFFICIENT 0 002 C OPERATING AMBIENT RANGE 14 to 122 F 10 to 50 C 0 to 80 RH
21. CR code the CR code is automatically sent after the string when using the PRINT statement without a semicolon at the end If several commands are sent using separate PRINT statements a proper delay is needed between the commands to give the CL521 time to execute the earlier commands No other commands can be series connected to the same command string after a V command The special function commands S1 to S5 can be used when the CL521 is in the MEASUREMENT mode Return to normal measurement is done with the S0 command For example a reference junction temperature message is requested with the command string S5P1S0 However the command S5 can also be used in the CALIBRATION mode in the CALIBRATION mode the reference junction temperature message is requested with the command string S5P1 and the reading is displayed until the next V command is received Instead of the upper case command characters the respective lower case characters can also be used 35 90 100 110 120 130 kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk This example program communicates with the CL521 It is made for an IBM PC compatible microcomputer The language is Microsoft GW BASIC K E k k k k o k k k k kkk kk k k kk kek kkk kok k kok k kk k eok kk k kok dokk ERE EKER Open the RS232 line for both input and output as a file No 1 The baud rate is set to 600 bit s no parity bit N the data format is eight data bits
22. cy the CL521 can measure any of ten thermocouple types platinum RTDs millivolts or ohms The CL521 is also an instrument calibrator allowing users to calibrate or check the above sensor type instrumentation The CL521 is designed for ease of use with a large easy to read LCD display with 0 41 10 4 mm digits A touch sensitive keypad makes function selection and value entry fast and easy while a toggle switch simplifies selection between measurement and calibration functions The CL521 can store up to six values for quick selection of common calibration temperatures as well as store six measurement readings Other features include rate of change calculation min and max storage and differential measurement from a stored value The CL521D has all the features of the CL521 with the addition of RS 232C two way communications and an analog output The RS 232C communications can be used for remote computer control of the unit as well as for transmitting data to a computer printer or datalogger The analog output is a 1 mV per degree signal with 10x amplification when using the differential function of the CL521D Each unit is supplied complete with carrying case connector leads type K thermocouple extension cable with male connector calibration certificate TAS U 5 connector and AC power adapter 1 2 FEATURES Calibrate and Measure J K T E R S B and N Thermocouples Measure 100 ohm Pt RTDs Math Functions Calculate Rate of Cha
23. display points to mV change the units to temperature by pressing the TC mV key once Select the required thermocouple type by repeatedly pressing the TC TYPE key until the arrow at the top of the display indicates the requested type Select the required reference junction compensation mode by repeatedly pressing the CJ MODE key until the arrow at the left edge of the display indicates the required mode If the Open Input Check used in the instrument being checked disturbs the CL521 operation it must be switched off during the time of simulation Temperature unit N CC EL Thermocouple Store value into type a memory register Recall Reference a register value junction mode Enter a simulation value to the TC amp mV connection Calibration Increase decrease Switch on the simulation value Figure 7 4 CL521 Calibrator Thermometer 24 The CL521 now operates as a thermocouple simulator continuously maintaining an output potential at the thermocouple terminals which corresponds to the value shown on its display If for example the potential changes due to a change in load the display is cleared until the CL521 has corrected the potential to the correct value The temperature units shown are the ones most recently used To change the temperature units press the C F key once The CL521 has the ability to simulate ten commonly used thermocouple types To simulate some other thermocouple
24. e OMEGA ENGINEERING INC is not responsible for any damages or losses caused to other equipment whether direct indirect incidental special or consequential which the purchaser may experience as a result of the installation oruse of the product The buyer s sole remedy for any breach of this agreement by OMEGA ENGINEERING INC or any breach of any Warranty by OMEGA ENGINEERING INC shall not exceed the purchase price paid by the purchaser to OMEGA ENGINEERING INC for the unit or units or equipment directly affected by such breach Every precaution for accuracy has been taken in the preparation of this manual however OMEGA ENGINEERING INC neither assumes responsibility for any omissions or errors that may appear nor assumes liability for any damages that result from the use of the products in accordance with the information contained in the manual PC keke PAS py Es AE ee tex ee EY vote eset erga 3 5 Direct all warranty and repair requests inquiries to the OMEGA ENGINEERING Customer Service Department call Toll Free 1 800 622 2378 FAX 203 359 781 1 International 203 359 1660 FAX 203 359 7807 BEFORE RETURNING ANY PRODUCT S TO OMEGA YOU MUST OBTAIN AN AUTHORIZED RETURN AR NUMBER FROM OUR CUSTOMER SERVICE DEPARTMENT IN ORDER TO AVOID PROCESSING DELAYS The assigned AR number should then be marked on the outside of the return package and on any correspondence FOR WARRANTY RETURNS please have the FOR NON WARR
25. e characters from each other The CL521 is wired as a RS 232C standard DTE type device The characters transmitted are coded according to the 7 bit ASCII code The bit b7 just before the stop bit is always set to zero When receiving characters from the computer the CL521 does not care about the state of the bit b7 start bit stop bit ies bg by bz b3 b bs bg b7 4 1 ze Figure 8 2 Serial Data Format The data format of the computer or the printer must be set to conform to the data format of the CL521 The proper settings are no parity bit one stop bit eight data bits In some devices the number of data bits is always seven and the eighth bit is used as a parity bit Those devices must be set so that no parity check is done for the received data In addition to the common data format of the connected devices they also must use the same data transmission rate The rate is measured in units of bits s baud The baud rates used in the CL521 are 150 bits s or 600 bits s The rate is selected with a switch on the option card see Figure 8 1 If the baud rate switch position is changed after the CL521 is switched on the new rate setting is not recognized until the CL521 is switched OFF and ON again 8 2 2 Connection Cables Connection cables for a computer or a printer are not supplied with the CL521 due to microcomputer manufacturers using different pin configurations or even different connector types on their computers
26. e power is switched on Otherwise Check that the MEASUREMENT CALIBRATION switch is in the MEASUREMENT position Choose thermocouple measurement by pressing the TC amp mV key If the display is showing millivolts an arrow at the right edge of the display is pointing to mV change it to temperature display by pressing the TC mV key once An arrow at the upper edge of the display will now indicate the most recently used thermocouple type Select if needed the required type by pressing the TC TYPE key repeatedly Select the required reference junction compensation mode by pressing the CJ MODE key repeatedly until the arrow at the left edge of the display is pointing to the required mode The CL521 will now measure potential from a thermocouple and convert it according to the NIST Conversion Tables to a temperature reading The temperature units C or F will be the ones most recently used To change the temperature units press the C F key once Temperature units Temperature mV selection Thermocouple type Reference junction mode selection Input sensor type selection Er ano 71 gg SEU Switch on Measurement Figure 4 11 CL521 Calibrator Thermometer A specific temperature measurement range has been defined for each type of thermocouple If the measured temperature is outside this range the display flashes the corresponding minimum or maximum temperature If the reference junctio
27. ement circuit resistance when meter movement indication devices are used to measure thermoelectric potential to predict the expected lifespan of a thermocouple by monitoring the change in its resistance as a function of time and comparing the measured values to data collected from previous experiences for various checks when accuracy requirements do not warrant the use of three or four wire connections for example to determine the wire order when connecting a three or four wire probe 13 4 5 MEASURING MILLIVOLTS If the instrument was most recently used for mV measurement it will be ready to use once the power is turned on If it was not recently used for mV measurement Check that the MEASUREMENT CALIBRATION switch is in the MEASUREMENT position Select the mV input by pressing the TC amp mV key Check that the measured value is shown in millivolts an arrow at the right edge of the display will point to mV if mV is not being shown press the TC mV key once 10 110 mv Temperature mV selection CJ MODE MAN Input connection Switch on selection Measurernent Figure 4 14 Measuring Millivolts with the CL521 The CL521 will now measure millivolts Reference junction compensation is automatically disconnected the CJ MODE arrow indicates MAN and Register 9 is set to 0 C If the potential being measured goes below 10 mV or above 110 mV the display will blink the minimum or maximum meas
28. es lr Displacement Transducers LY Instrumentation amp Accessories FLOW LEVEL 4 Rotameters Gas Mass Flowmeters amp Flow Computers 4 Air Velocity Indicators 4 Turbine Paddlewheel Systems f Totalizers amp Batch Controllers pH CONDUCTIVITY A pH Electrodes Testers amp Accessories 4 Benchtop Laboratory Meters 4 Controllers Calibrators Simulators amp Pumps A Industrial pH amp Conductivity Equipment DATA ACQUISITION 4 Data Acquisition and Engineering Software A Communications Based Acquisition Systems AT Plug in Cards for Apple IBM amp Compatibles 4 Datalogging Systems f Recorders Printers amp Plotters HEATERS 4 Heating Cable 4 Cartridge amp Strip Heaters 4 Immersion amp Band Heaters 4 Flexible Heaters 4 Laboratory Heaters
29. f the unit and replace it with the option Connect the option to connector J3 on the main board as shown in Figure 8 1 Make sure that the front end of the card fits into the guiding slot Before screwing the option to the rear panel of the CL521 check the position of the baud rate switch see Section 8 2 1 After replacing the upper cover of the CL521 the option is ready for use 600bit s 4m 150bit s baud rate switch connector J3 guiding hole Figure 8 1 Installing RS 232C Option 28 8 2 1 Data Format and Baud Rate The digital interface puts out measurement results to a printer or enables the CL521 to be remotely controlled by a computer The interface is isolated from the measurement circuits of the CL521 by means of optocouplers and a DC DC converter The digital interface is a serial interface conforming to the RS 232C standard The standard was originally intended to be used in interfaces between data terminal equipment DTE and data communication equipment DCE but it is also widely used in interfaces between microcomputers and peripheral devices like printers The characters are binary coded and transferred in serial form using only one line The beginning of the transfer of each character is indicated by one start bit of logic zero positive voltage The eight data bits of characters are transferred beginning from the least significant bit At least one stop bit of logical one negative voltage is needed to separate th
30. ftware involved with the CL521 In some cases this means that the effect of an adjusting operation will not be seen on the display until after approximately one minute After turning a trimmer always wait until you can see the effect on the display Connect the voltage standard to TC mV In Out terminals and select mV measurement The reference junction compensation must be switched off CJ is MAN and 0 C set in Register 9 The display can be corrected to the right reading if necessary using trimmer R7 on the main board Next calibrate the resistance measurement mode Connect the resistance standard to the Pt100 in terminals of the CL521 and select ohm measurement If necessary adjust the trimmer Pt100 SPAN at the front of the terminal panel until the display reading is correct The next calibration step is the internal reference junction compensation Select thermocouple measurement type K thermocouple and internal reference junction compensation Connect the type K thermocouple probe and put it into a 0 C ice bath or OMEGA TRCIII The display should show 0 C If necessary adjust the display reading to the correct value using the CJ ZERO trimmer at the front of the terminal panel If there is a CL521 RS232C Option card installed in the unit check the calibration of the analog output signal The calibration can be done with a resistor of approximately 300 ohms connected to the TC mV in Out terminals of the CL521 First switch the
31. ing case be sure the AC adaptor is not connected then open both carrying case flaps and the strap around the instrument Lift the rear of the instrument about an inch lift the front of the instrument and pull it out of the case The unit s carrying handle may then be turned downwards in front to act as a stand for easier viewing The unit is installed into its case in the reverse order In the field the carrying case is most convenient When carried around the neck the unit can easily be used merely by opening the flap in front of the panel and turning it over to the back of the case Figure 2 1 Removing the Carrying Case 2 3 CHARGING THE BATTERY The power used by the unit comes from the internal battery which also keeps certain program parameters in memory even when the unit is switched off The unit comes with its battery partially charged and it is therefore advisable to charge the battery before use When the rechargeable batteries in the instrument begin to run down the message BATTLO appears periodically on the display If the battery voltage goes too low the instrument switches itself off to prevent destructive discharge of the batteries and loss of data stored in the memory registers i When BATTLO appears on the display the battery should be recharged as soon as possible Plug the charger cable into the connector at the rear of the unit Connect the charger to the 120 VAC making sure that the line voltage is correc
32. it using the Up and Down arrow keys until the measuring device shows the required reading If the necessary correction is large press the arrow key for a longer time After one second the calibration value will begin to change at a progressive rate Release the key before the measuring device indication approaches the required value and continue with single steps if necessary Each thermocouple type has been assigned a specific simulation range If values outside this range are used the display will flash the corresponding maximum or minimum value If the compensation temperature goes outside the range of 10 to 70 C the display will indicate CJ LO or CJ HI correspondingly 7 2 3 The Effect of Loading The CL521 thermocouple output is restricted to about 0 6 mA E 60 mV Thus the Stabilization time of the simulation value increases when devices that cause circuit loading such as wirewound meter movement devices are being checked If the device contains a short circuit or if the resistance of the device to be checked is too low OLOAd is displayed If reaching the simulation value takes more than about two seconds the resistance of the measuring device is so small that the effect of the lead resistance must also be considered Wirewound meter movement devices used in conjunction with thermocouples are normally calibrated for proper indication when the total lead resistance of the conductors is known commonly ten or twenty ohms The
33. king is used in the data transfer F P1 causes output of one message and disables the automatic output If the CL521 is just putting out the latest automatic message it may disturb the program operation therefore it is best to neglect the first requested message with a proper delay before opening the RS 232 input The delay Opens the RS 232 input as File No 1 Thermocouple measurement with TC type K is selected and one output message requested Keypad operations are allowed Receives an input message Check of M C switch position Check of measuring unit Check of connections Program heading 34 110 START 1 Make sure that the initial reading is printed 120 PRINT 2 P1F0 Request and receipt of an 130 INPUT 1 L input message from the CL521 140 T VAL MID L 10 8 Separation of the reading 150 IF ABS T XT gt 0 5 If the temperature is changed 1 2 degree OR START 1 THEN or more the time and the temperature LPRINT TIME LPRINT are printed USING C T 160 START 0 XT GOTO 120 Next measurement The output of the example program could be the following 09 28 12 124 3C 09 28 45 124 8C 09 29 03 125 2C The computer commands to the CL521 may be series connected in strings as written in the example program The maximum length of a command string is 20 characters The execution of the commands is started only after the entire string is received The CL521 notices the end of the string after receiving a
34. ly selected from the keypad on the front panel CL521 functions are listed below and shown in Figure 3 1 For more complete instructions refer to Sections 4 to 7 THERMOCOUPLE MEASUREMENTS Temperature measurement in either C or F using ten different thermocouple types Reference junction modes External reference junction if the temperature value is not 0 C must be entered into the memory Reference temperature is measured using a Pt100 0 00385 resistance probe Reference temperature is measured using an internal sensor Millivolt measurement 10 to 110 mV Thermocouple resistance measurement RESISTANCE MEASUREMENT Temperature measurement in C or F using a Pt100 0 00385 resistance probe Ohm measurement 0 to 400 ohms ADDITIONAL MEASUREMENT FUNCTIONS Rate of change measurement Measurement of deviation from a preset value Storage of minimum and maximum values CALIBRATION FUNCTIONS Thermocouple simulation in C or F Millivolt calibration 10 to 110 mV Entry of calibration values From keypad From memory Smooth increase or decrease Fine adjust using INC and DEC switches Automatic stepping through five preset calibration values Kk seelbap uj ain3eJedujaj uon oun aoussajas ejdnoooueu 6 Spou 43510 uonsi ep JO eJnie1eduig3 uosjjeduoz 8 ZT 8 dn 34636 393j8 anea Jeyrug epuoaes 0001 indino paddays oyewoyne up uibue daas 1
35. n temperature goes below 10 C or above 70 C the unit displays CJ LO or CJ HI respectively 11 4 3 3 Checking and Setting Reference Junction Temperature The temperature in the reference junction compensation circuit or the compensation temperature of an external compensation circuit may be set to a temperature other than 0 C The external reference junction temperature may also be measured by methods other than a Pt100 probe In all these cases manual compensation for reference junction temperature must be used and that temperature value stored into memory Register 9 The value in Register 9 indicates the temperature of the reference junction in C regardless of the selected temperature units Register 9 is automatically set to zero whenever the manual reference junction compensation mode is selected To check the reference junction temperature or to change it proceed as follows NOTE Make sure the MAN reference junction compensation mode is selected Switch the MEASUREMENT CALIBRATION switch to the CALIBRATION position Recall Register 9 the reference junction temperature to the display by entering RCL 9 The display will show for example CJ 0 00 C To set the reference junction compensation temperature to 50 C for example enter 50 STO 9 After checking and or setting the reference junction temperature return the MEASUREMENT CALIBRATION switch back to the MEASUREMENT position Setting reference ju
36. nction ta temperature Checking reference junction temperature eMe tot 8 1 oe re Fc innnr 1l lot UU UL i Calibration Figure 4 12 Checking and Setting Reference Junction Temperature 12 The reference junction temperature in Register 9 can also be checked while using the internal reference junction compensation INT or while measuring the reference junction temperature with a Pt100 probe PROBE 4 4 MEASURING THERMOCOUPLE RESISTANCE The CL521 can be used to measure the resistance of a thermocouple circuit during thermocouple temperature measurements The measurement will yield a correct resistance regardless of the prevailing thermoelectric potential Display the circuit resistance by pressing the TCQ key while in TC amp mV mode Return to the normal measurement mode by pressing the TC amp mV key Select TC Q measurement Cra fi plana sen Lu Tele Measurement Return to temperature or mV measurement Figure 4 13 Measuring Thermocouple Resistance with the CL521 The resistance measurement range is 0 to 400 ohms Exceeding this range causes the display to blink the maximum allowed resistance If the measurement circuit is broken the display will indicate OPEN Thermocouple resistance measurements can be used to determine the condition of the measurement connections and to help locate short circuits to help in adjusting the measur
37. nge and Difference Min Max Storage Store up to Six Simulations for Quick Recall Enter Calibration Values Directly from Keypad or Through Up Down Increment Keys e Available with Optional RS 232C and Analog Output e o o o 9 1 3 AVAILABLE MODELS MODEL NUMBER DESCRIPTION CL521 Temperature calibrator indicator CL521D Calibrator with RS 232C and analog output CL521 RS232C RS 232 interface board includes software CL521 MA Milliamp board with 24 Vdc supply SECTION 2 INSTALLATION 2 1 UNPACKING Remove the packing list and verify that all equipment has been received If there are any questions about the shipment please call the OMEGA Customer Service Department at 1 800 622 2378 Upon receipt of shipment inspect the container and equipment for any signs of damage Take particular note of any evidence of rough handling in transit Immediately report any damage to the shipping agent NOTE The carrier will not honor any claims unless all shipping material is saved for their examination After examining and removing contents save packing material and carton in the event reshipment is necessary All units are supplied with carrying case connector leads type K thermocouple extension cable with male connector calibration certificate TAS U 5 connector and AC power adapter 2 2 REMOVING THE CARRYING CASE In laboratories and maintenance shops the CL521 is easiest to use without its carrying case In order to remove the carry
38. nsor This is a simple method to account for reference junction temperature Remember to use the correct type and polarity of extension wires Thermocouple 8c extension To device being checked Simulation temperature PRECISION THERMOMETER CALIBRATOR WIESE I Figure 7 1 Internal Reference Junction Compensation with the CL521 B REFERENCE JUNCTION COMPENSATION USING A Pt100 PROBE CJ MODE PROBE The CL521 is connected to the measuring circuit with copper wires An extra thermoelectric potential occurs at the point where the copper conductors are attached to the thermocouple extension wire The temperature at this point is measured with a Pt100 probe connected to the CL521 When using this method no problems arise from connection wire type and polarity It is however necessary to place the Pt100 probe at the connections so that it will be at the same temperature as the connections for which the compensation is necessary 22 To device being checked Thermocouple extension Simulation cable temperature CM H pi S HSA NEA UC UDBUN ii Figure 7 2 Reference Junction Compensation Using a Pt100 Probe to Measure the Reference Junction C MANUAL REFERENCE JUNCTION COMPENSATION CJ MODE MAN The manual mode is used if the device being checked does not have reference junction compensation or compensation has been disconnected The CL521 is connected directly to
39. ormally T1 is measured while the reference junction temperature is kept at a constant temperature T2 or is somehow compensated for during evaluation of the measured value Frequently the circuit is broken at the reference junction Thus the reference junction is moved to the point where the connection is made from the thermocouple conductors to the copper wires Figure 4 3 Thermocouple with Reference Junction and Voltmeter 4 2 REFERENCE JUNCTION TEMPERATURE The reference junction temperature is easiest to compensate for by measuring the temperature of closely situated reference junctions using for example a resistance temperature probe rs A Cu Tta lt B i Cu _ l M 1 Feu A Cu Tib 1 I lt 8 Cu I I i Figure 4 4 Reference Junction Compensation Using a Pt100 Probe The temperature of the reference junctions can also be kept constant by cooling or heating them with the aid of a thermostat When cooling 0 C is most convenient When heating a temperature is selected which is somewhat hotter than room temperature for example 50 C Temperature controller Figure 4 5 Reference Junction Compensation Using a Temperature Controller 7 The reference junction can also be placed into a compensation circuit A temperature sensor measures the reference junction temperature and feeds a correction potential into the measurement circuit as the reference junction temperature varies Thus the temperatu
40. re of the reference junction appears constant to the measurement circuit The compensation temperature is normally 0 C Reference Junction Temperature Sensor To Instrument Bre O Q O O Thermocouple Figure 4 6 Electronic Reference Junction Compensation Circuit 4 3 THERMOCOUPLE MEASUREMENTS 4 3 1 Connections and Reference Junction Mode Selection Connect the thermocouple wires if it has not been done already Use the polarity marked on the terminal panel Carefully consider whether you shall use copper leads or thermocouple extension cables The extension cable must conform to the thermocouple both by type and polarity If the external reference junction temperature is to be measured also connect a Pt100 probe The CL521 incorporates three different reference junction modes A Internal reference junction compensation CJ MODE INT B External reference junction compensation using a Pt100 probe CJ MODE PROBE C Manual reference junction compensation CJ MODE MAN A INTERNAL REFERENCE JUNCTION COMPENSATION CJ MODE INT The thermocouple is connected directly or through thermocouple extension cables to the CL521 thermocouple terminal posts This is the most common method of compensation for reference junction temperature but you must use the correct type of thermocouple extension cables Thermocouple extension cables Sere TES Figure 4 7 Measurements Using Thermocouple Ex
41. rement circuit is broken the display will indicate OPEN If the temperature reading of the Pt100 sensor is unreasonable or the display indicates OPEN the Pt100 sensor is probably broken or incorrectly connected The TCQ measurement function can now be used to determine the correct lead assignments First determine the probe wiring Then determine three or four wire lead assignments by systematically measuring resistances between the various leads The TCQ function is switched on by pressing the TC amp mV key followed by the TCQ key Return to the Pt100 measurement mode by pressing the Pt100 key 18 Figure 5 7 Basic methods of ohm and Pt100 measurement connections a Four Wire Connection b Three Wire Connection C Two Wire Connection with Compensation Loop 5 4 RESISTANCE MEASUREMENT The CL521 can also be used to measure resistances The resistance measurement mode is selected by pressing the Q key The resistance to be measured is connected like a Pt100 probe using a three or four wire connection The arrow at the top of the display indicates Pt100 sensor resistance measurements The arrow at the right edge of the display indicates basic Q measurements Switch on Measurement Figure 5 8 Resistance Measurement with the CL521 The resistance measurement range is 0 to 400 ohms If the measured resistance is abov e this range the display will blink the maximum value to indicate range overflow If the measuremen
42. s 0 01 ohm Pt100 range 850 C to 1200 C is extrapolated from DIN 43760 curve Pt10 Rh Pt 0 05 e ii z 39 Servicing USA and Canada Call OMEGA Toll Free OMEGA Engineering Inc One Omega Drive Box 4047 Stamford Connecticut 06907 0047 Headquarters 203 359 1660 Sales 1 800 826 6342 1 800 TC OMEGA USA and Canada Customer Service 1 800 622 2378 1 800 622 BEST USA only Engineering Assistance 1 800 872 9436 1 800 USA WHEN USA only FAX 203 359 7700 TELEX 996404 EASYLINK 62968934 CABLE OMEGA Servicing Europe United Kingdom Sales amp Distribution Center OMEGA Technologies Ltd P O Box 1 Broughton Astley Leicestershire LE9 6XR England Telephone 0455 285520 FAX 0455 283912 The OMEGA Complete Measurement and Control Handbooks amp Encyclopedias NM Temperature pH and Conductivity Pressure Strain amp Force Data Acquisition Systems Flow and Level Electric Heaters AEEPERATURE Call for Your FREE Handbook Set Today 203 359 RUSH OMEGA Your Source for Process Measurement and Control TEMPERATURE EY Thermocouple RTD amp Thermistor Probes Connectors Panels amp Assemblies f Wire Thermocouple RTD amp Thermistor f Calibrators amp Ice Point References 4 Recorders Controllers amp Process Monitors A Infrared Pyrometers PRESSURE STRAIN FORCE A Transducers amp Strain Gauges 4 Load Cells amp Pressure Gaug
43. s the functioning of the thermocouple The simulator is given a temperature value which it then converts into a corresponding potential To the measuring device the simulator appears as a thermocouple at the set temperature Thermocouple simulation can be used to check temperature indication devices plotters transmitters and other equipment related to a thermocouple probe If thermocouple extension cable is used in the measuring circuit an extra thermovoltage will be created at the point where the simulator is connected to the extension cable The simulator must be able to compensate for this extra potential 7 2 THERMOCOUPLE SIMULATION 7 2 4 Connection and Selection Compensation Modes All reference junction compensation modes of the CL521 can be used in thermocouple simulation Compensation is needed for thermopotentials arising from simulator connection into the measuring circuit The choices are A Internal reference junction compensation CJ MODE INT 21 B Reference junction compensation using a Pt100 probe CJ MODE PROBE C Manual reference junction compensation CJ MODE MAN A INTERNAL REFERENCE JUNCTION COMPENSATION CJ MODE INT The CL521 replaces the thermocouple in the measurement circuit and is connected with thermocouple wire or thermocouple extension wire The thermoelectric potential created by the connections at the simulator binding posts is automatically eliminated with the aid of the internal temperature se
44. sends two end characters In start up the end characters are set to CR and NUL ODH and 00H CR Carriage Return returns the printer carriage and in many printers it also feeds the paper one line auto line feed The printers normally neglect the NUL code If the printer cannot be set to the auto line feed mode a LF Line Feed code OAH is needed to feed the paper The end characters may be changed by connecting a computer to the digital interface and entering the command Y1FO or Y2F0 see Section 8 2 5 The new end characters set by the computer are used until the CL521 is switched off 8 2 5 Remote Control by Computer The operation of the CL521 can be controlled by a computer connected to the digital interface After a command from the computer is received all further keypad operations are neglected until the FO command from the computer is received The usable computer commands are listed below A Function selection FO Allows front panel operations F1 Selects thermocouple measurement calibration mode F2 Selects resistance measurement F3 Selects Pt100 measurement F4 Selects thermocouple resistance measurement thermocouple measurement must be selected before the F4 command B Special function selection SO Returns to normal operation S1 Displays the minimum reading S2 Displays the maximum reading S3 Deviation measurement S4 Displays the rate of measurement change S5 Displays the reference junction temperature
45. stance of the compensation lead loop is equal to the resistance in the measurement loop The properties of this method resemble those of the three wire method A measurement circuit utilizing a compensation loop is connected to the CL521 similar to the three wire method Bro ps Figure 5 5 Connecting a 2 Wire Resistance Probe with a Lead Compensation Loop to the CL521 5 3 Pt100 TEMPERATURE MEASUREMENT Connect the probe directly or through a connecting cable to the CL521 No line resistance trimmers are needed Use four wire connections if possible if the CL521 was most recently used for Pt100 measurements it is ready to use once the power is switched on If it was not recently used for Pt100 measurement Check that the MEASUREMENT CALIBRATION switch is in the MEASUREMENT position Select Pt100 measurement by pressing the Pt100 key 17 Switch on Measurement Figure 5 6 Pt100 Temperature Probe Measurement with the CL521 The display will indicate the probe temperature while an arrow at the top of the display indicates Pt100 measurement mode The displayed temperature units are those most recently used To change the temperature units press the C F key once Pt100 temperature measurement works in the range of 200 to 1200 C If the probe temperature goes below or above this range the display will blink the minimum or maximum value to indicate range underflow or overflow If the measu
46. t Charge the battery for approximately 12 hours 20 hours if used during charging 2 4 WIRING CONNECTIONS The CL521 connection terminals are found on top of the unit Connections are easily made and wires are kept out of the way of the display and keypad When using the CL521 in its carrying case the flap in front of the connection panel may be shut during use This reduces changes in reference temperature of thermocouple temperature measurements thus ensuring measurement accuracy in environments where ambient temperature may vary greatly The terminal panel contains two separate types of connections The TC and mV connection is used for thermocouple and millivolt measurement and simulation calibration When the MEASUREMENT CALIBRATION switch is in the MEASUREMENT position this connection measures inputs The CALIBRATION position provides a calibration output signal The resistance of a circuit connected to the TC and mV connection may also be measured by using the TCQ measurement function The Ohm and Pt100 connection is used to measure the resistance of Pt100 or other resistive probes Both three and four wire connections are possible Used in four wire connections TC and mV connection Ohm and Pt100 connection Figure 2 2 Terminal Panel 3 SECTION 3 GENERAL OPERATION 3 1 FRONT PANEL FUNCTIONS The functions of the CL521 have been chosen for their usefulness in temperature measurement and calibration The functions are easi
47. t circuit is broken the display will indicate OPEN 19 Resistance measurements can be used for example to determine temperature using resistance probes other than the Pt100 In applications not requiring high accuracy it is often more convenient to use the two wire TC Q measurement mode SECTION 6 ADDITIONAL MEASUREMENT FUNCTIONS 6 1 USING OTHER MEASUREMENT FUNCTIONS The additional measurement functions may be used whenever the MEASUREMENT CALIBRATION switch is in the MEASUREMENT position Additional measurement function keys Figure 6 1 Additional Functions with the CL521 To return to the normal measurement mode from another measurement function press the NORM key 6 2 MONITORING RATE OF CHANGE The rate of measurement change is normally calculated from the change occurring during a period of 12 seconds If the change is very small however the period is automatically stretched up to two minutes to get better resolution The change in rate display is obtained by pressing the RATE key The function is indicated by the letter r at the left side of the display The value is shown in C min F min mV min or ohm min This function is intended for use mainly to facilitate monitoring of temperature stabilization in a calibration oven 6 3 MEASUREMENT OF DEVIATION Pressing the DIFF key causes the deviation from the value stored in Register 8 to be shown on the display This function is indicated by the letter d
48. tched OFF Depending on the method the computer uses in reading the messages of the CL521 the change of the end character combination may also provide changes to the computer programs YO End characters of a message are CR ODH and NUL 00H Y1 End characters of a message are CR 0DH and LF OAH Y2 End characters of a message are LF OAH and CR 0DH The computer program for the CL521 control is easy to write using BASIC language The details of the program depend on it s purpose the BASIC used and the computer The example program is for an Epson HX 20 microcomputer The language conforms to the widely used Microsoft BASIC except in reading the time and opening the serial communications channels 33 10 OPEN O 2 COMO 38N1F 20 PRINT 2 P1 30 FOR T 0 TO 1000 NEXT 40 OPEN I 1 COM0 38N1F 50 PRINT 2 F1T6P1F0 60 INPUT 1 L 70 IF LEFT L 1 lt gt M THEN PRINT Turn the M C switch PRINT to MEASUREMENT PRINT and press RETURN CLS INPUT A GOTO 50 80 IF RIGHT L 1 lt gt C THEN PRINT Select Celsius PRINT as the meas unit PRINT and press RETURN CLS INPUT A GOTO 50 90 CLS PRINT Check the wiring PRINT and CJ mode PRINT and press RETURN INPUT A CLS 100 PRINT TRACKING OF PRINT TEMPERATURE PRINT CHANGES Opens the RS 232 output as File No 2 The baud rate is set to 600 bits s 3 the data format is eight data bits 8 no parity bit N and one stop bit 1 No hand sha
49. tension Cables In the field the ambient temperature may change suddenly Under such conditions accurate reference junction compensation can be ensured by closing the flap on top of the terminal panel during use The instrument is shipped complete with a connecting cable for a type K thermocouple Connect the miniature connector on the cable to the terminals according to the polarity shown Oo O 19 1 9 c 2 Pt100 In Figure 4 8 CL521 Terminal Panel 9 B REFERENCE JUNCTION COMPENSATION USING A Pt100 PROBE CJ MODE PROBE In this mode the reference junction T2 is outside the CL521 at a location where a Pt100 probe is also installed The thermocouple is connected to the CL521 with copper wires and the Pt100 probe is connected to the Pt100 terminals Figure 4 9 Reference Junction Compensation Using a Pt100 Probe C MANUAL REFERENCE JUNCTION COMPENSATION CJ MODE MAN Reference junction temperature compensation is automatically set to 0 C using the external reference junction The thermoelectric potential is connected to the CL521 using copper leads External Reference Junction OMEGA CJ Sere CJ MODE 3 ies OE MAN Figure 4 10 Manual Reference Junction Compensation 10 4 3 2 Measuring Temperature Once connections are completed measurements can be performed If the CL521 was most recently used for the same type of measurements it is ready to use once th
50. type millivolt calibration must be used and millivolt values must be obtained by utilizing a temperature to millivolt conversion table There are many methods of entering new calibration values Entering new values with the numeric pad To enter for example 25 C enter 25 ENT Recalling values from memory Registers 0 to 6 Frequently used calibration values can be stored into memory Registers 0 to 6 The register values are kept in memory even if the CL521 is switched off For example to store the value 625 3 into Register 3 enter 625 3 STO 3 To use the contents of memory Register 3 as a calibration value enter RCL 3 ENT Stepping through preset values Memory Registers 0 to 4 can be used to hold convenient test values such as 0 25 50 75 and 100 of full scale The CL521 can be set to step through these simulation values Automatic stepping is started by entering RCL ENT and is stopped by pressing the CL key or any numeric key The duration of each simulation value in automatic stepping is preset to 12 seconds If necessary the duration can be changed by storing a new duration time in the range of 5 to 1000 seconds into Register 7 For example to set the duration to 60 seconds enter 60 STO 7 25 Increasing or decreasing the output signal smoothly If the measuring device must be made to show some specific steady reading first enter the corresponding calibration value from the numeric pad and then change
51. urement values to indicate range underflow or overflow SECTION 5 Pt100 RESISTANCE MEASUREMENTS 5 1 GENERAL INFORMATION Resistance probes are often used for temperature measurement Currently the most common probe type is the Pt100 resistance probe It is constructed from platinum wire having a resistance of 100 ohms at O C The resistance increases with temperature because metal wires have a positive thermal coefficient of resistance 14 In measuring the resistance of a probe the effect of lead wire resistances between probe and measuring device must be compensated for Normally the change of the lead resistance as its temperature changes must also be considered Accurate measurements require that the connecting cable have at least three and preferably four conductors 5 2 CONNECTING A RESISTANCE PROBE ideally the best method of eliminating the effect of lead resistance is to use four conductors when measuring the temperature with the probe Two conductors are required to carry the measurement current through the resistance while the other two are used to measure the voltage across the probe Constant current 222 Q ae esie cs R AE Figure 5 1 Basic Pt100 Measuring Circuit The CL521 uses this method in resistance measurements By measuring potentials both with and without current flow the unit can also eliminate possible thermoelectric potentials caused by conductor connections Pt100
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