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15 

BASIC UNIT 

5.4.2  Cold Junction Compensation 

When using thermocouples to measure temperature it is almost always 
necessary to know the temperature of the ”cold junction”. Thermoelectric 
voltage has to be ”adjusted” with respect to this temperature. 
Thermoelectric voltage is the result of the 

temperature difference 

between 

the cold junction and the hot junction. 
A solid state temperature sensor has been placed centrally in the screw 
terminal area of the analogue board. Its temperature is automatically sampled 
every time a temperature measurement is taken. All temperature 
measurements are thus compensated for the actual temperature of the 
terminals themselves. 
 
Some precautions have to be taken if the ”3100i” is exposed to rapid 
temperature gradients. Since temperature is measured in one point only, a 
gradient from one side of the unit to the other may cause misreadings. 
 
By giving the unit time to reach a stable temperature before recordings are 
started and by protecting it from sudden changes of ambient temperature a 
very high degree of accuracy can be achieved. 

Summary of Contents for PC-Logger 3100i

Page 1: ...How to use PC logger 3100i and accessories INTAB Interface Teknik AB e mail info intab se www intab se...

Page 2: ......

Page 3: ...RS 16 6 1 Power 16 6 2 Computer 16 6 3 Connecting Sensors and Transducers 17 7 MISCELLANEOUS 23 7 1 Reset 23 7 2 Program 23 8 TECHNICAL SPECIFICATIONS 24 8 1 Analog Data 24 8 2 Storage Memory 26 8 3 C...

Page 4: ...Temperature Measurements with Pt 100 Sensors 38 2 DESCRIPTION 39 3 CONNECTING SENSORS 40 3 1 Screw Terminals 40 3 2 Measurement Methods 41 4 TECHNICAL DATA 44 OPTION MODEM PORT 45 1 DATA FORMAT 45 2 C...

Page 5: ...tops The scope of this manual is to enable the user to correctly connect transducers and use the 3100i off line How the 3100i is handled using our software and a PC is explained in the program manuals...

Page 6: ...tionally expansion memory Off line measurements should be preceded by the transferral of measurement parameters from the computer to the 3100i These parameters contain among others see program manual...

Page 7: ...l is then shown every three seconds Try this feature by pressing the intab logo RECORD is selected when you intend to collect data Verify your choice with OK See illustration below Starting a new reco...

Page 8: ...f how the maximum length of a recording can be calculated from known parameters follows below It is assumed that recordings are made using software supplied by INTAB 3 1 Storage capacity in your compu...

Page 9: ...is then 6 seconds The formula will be 6 64 000 2 4 48 000 seconds or more than 13 hours The internal memory of the 3100i will only store one recording at a time Starting a new recording will erase th...

Page 10: ...st take up to about 15 minutes to charge to a point where the 3100i again will be operational Two days of charging should be enough to bring them up to full capacity Some applications require the 3100...

Page 11: ...source is correctly connected A signal cable consisting of a twisted pair can be very long if the lowest potential of the source is connected to ground via a separate cable The input ranges are set a...

Page 12: ...nnels have at least 25000 divisions A division is the smallest discernible change in input signal The resolution of an input can be expressed as FSR divided by the no of divisions Two examples a A 10V...

Page 13: ...ves the signal to 6 A Note that 4 20mA signals are beautifully transformed into correct magnitude and unit by the transform function of the software NOTE that the shunt resistor will overheat if subje...

Page 14: ...selecting type and range for your application K is the most common type Cold Junction 0 C TYPE mV at 200 C mV at 600 C mV at 1200 C MAX temp C K 8 137 24 902 48 828 1370 N 5 912 20 609 43 836 1300 J 1...

Page 15: ...terminal area of the analogue board Its temperature is automatically sampled every time a temperature measurement is taken All temperature measurements are thus compensated for the actual temperature...

Page 16: ...15VDC 2 0V 3 20 28VDC this is an alternative to pin 1 6 2 Computer 3100i connects to a serial port of the computer using the supplied spiral cable The 15 pin D SUB connector has the following pin out...

Page 17: ...NEL 7 CHANNEL 8 CHANNEL 15 CHANNEL 16 CHANNEL 23 CHANNEL 24 U I 13 14 15 16 U I 12 10 11 U I 21 22 23 24 9 CHANNEL 21 CHANNEL 22 CHANNEL 13 CHANNEL 14 CHANNEL 5 CHANNEL 6 GND GND U I 17 18 19 20 CHANN...

Page 18: ...al connection to signal ground Input block diagram Differential channels measure as the name implies the difference in voltage between the and input in relation to signal ground Another way of saying...

Page 19: ...ur signal paths To maintain the validity of your measurements you have to take the common mode range into account Common mode range is 10V for most ranges LOGGED SIGNAL CHANNEL GND ref MAX 10V COMMON...

Page 20: ...ombined but you have to make sure that your ground leads don t carry any current or connect to the same point from two directions Ground leads that carry current will at best ruin your measurements At...

Page 21: ...re must also be taken so that other equipment don t introduce common modes outside the permitted range Least problems should arise if the 3100i is inserted as near the most negative end of the loop as...

Page 22: ...ethods can be combined if care is taken to avoid ground loops 1 Signals with Common ground reference 1 2 GND DIFF Connect 3100i signal GND to system ground Connect sensors Place switch in position DIF...

Page 23: ...oftware Please consult your software manual for details Bootable files have the extension LDM The Intab PC logger software automatically selects the correct one if there are several present on the dis...

Page 24: ...3 Time Base X tal reference Uncertainty 20ppm at 20 C Stability 50ppm 20 C to 60 C 8 1 4 Inputs 8 16 or 24 differential inputs Impedance Overvoltage protection Min 400 k 30V continuous Higher voltages...

Page 25: ...ross the input by using the on board switch see 5 2 NOTE Max allowed current through shunt is 80mA 8 1 6 Divisions Min 25000 divisions 8 1 7 Resolution Examples Range Resolution approx 10V 0 4mV 1000m...

Page 26: ...on 0 5 C 8 1 9 Common Mode Common mode range CMR min 5V at 10V FSR min 10V other ranges min 80dB 8 2 Storage Memory Sizes 0k Bytes only for on line recordings 64k Bytes optional 64k 512k Bytes optiona...

Page 27: ...ntinuously trickle charged Capacity Min 2 hours of operation with fully charged accumulators 8 5 2 Charger Mains Adapter Voltage 12 15VDC Current Min 500 mA 8 6 Mechanical specifications Width 165mm L...

Page 28: ...28 INTAB Interface Teknik AB...

Page 29: ...card has the following I O s 4 digital outputs relays 8 digital inputs 6 of which are used as inputs to the counters 1 1 Digital Outputs Four digital outputs in the form of relay contact closures are...

Page 30: ...l input status is reflected in channel 31 The binary sum of active inputs are presented with DI1 as LSB 1 2 1 Opto isolated inputs The Opto isolated inputs DI1 DI8 are used to detect high level 10V si...

Page 31: ...volume They are therefore an excellent example of how the counters can be used to measure flow Counter values are presented in channels 25 through 30 2 1 Reset mode Reset mode will reset or zero the c...

Page 32: ...pter is able to supply and never more than 500mA Terminal configuration is shown in the illustration below DI 8b DI 8a DO 4b DO 4a DO 3b DO 3a DO 2b DO 2a DI 7b DI 7a DI 6b DI 6a DI 5b DI 5a DO 1b DO...

Page 33: ...ssible on DO1a b DO4a b see figure DIGITAL OUTPUTS RELAY SPST DO a DO b Switching Capability Power 30W 50VA Voltage 45V AC DC Current 1 25A AC DC N B No voltage above 45V may be applied to any part of...

Page 34: ...at mechanical contacts always bounce when brought together This bouncing will unless filtered result in a burst rather than one pulse VO GND OR DI b DI a PULSE MAX 24V OPTO ISOLATION ANY POLARITY DI a...

Page 35: ...olated Inputs No of inputs Low level High level Max input voltage Impedance Input current Max frequency 8 Max 4V Min 8V 30V Min 1k Ohms Max 30mA at 30V in Min 30kHz at duty cycle50 4 2 2 TTL compatibl...

Page 36: ...INTAB Interface Teknik AB 4 3 Auxiliary Power 4 3 1 for Opto Couplers Voltage mains adapter output max 15V Current mains adapter rating 300mA or max 200mA 4 3 2 for TTL Inputs Voltage 4 6V Impedance...

Page 37: ...that U R I I e the voltage across a resistor is the product of the current through it and its resistance Juggle the letters a bit and you get R U I School maths again As current I is known and consta...

Page 38: ...noted In four wire techniques total uncertainty is the sum of 3100i analog channel uncertainty and constant current uncertainty The analog inputs have an uncertainty of 300ppm Using the 100mV range a...

Page 39: ...es between 80ms and 100ms to sample The maximum time the constant current is flowing is actually only this long Therefore it never contributes to any self heating of the sensor What are the implicatio...

Page 40: ...ected to sensors 8 16 24 21 22 23 13 14 15 5 6 7 20 12 4 2 3 10 11 18 19 17 9 1 The constant current comes out of the terminal whenever the corresponding channel is sampled It should pass through the...

Page 41: ...lace in some applications A three wire version of the five wire method can also be employed where the demand for accuracy is small Three wire resistance measuring where the three wire device is part o...

Page 42: ...00 sensors It can of course be expanded to up to 24 sensors You realise of course that these can be combined with other sensors and transducers that don t require current sources Analogue board Consta...

Page 43: ...veloped by a similar current source across a reference resistor R2 The lead return resistance is with this method elegantly compensated for as it is included in both the minus and plus signal and thus...

Page 44: ...e contribute to a considerable measurement error This is how you go about connecting the three wires Compare this to the five wire method 0 500mA Constant Current 0 500mA Constant Current I R1 Pt 100...

Page 45: ...FORMAT The serial data format between the 3100i and a modem is 1 Start Bit 8 Data Bits 1 Stop Bit No Parity 2 CONNECTOR STANDARD The connections adhere to a subset of the RS 232C standard The connecto...

Page 46: ...grams how many rings that must arrive before the call is answered The commands have the following default settings BPA_0226 LDM or later INITANSWER ANSWER RING DIAL ATE0 ATA 3 Has no initial settings...

Page 47: ...choice have to be set up to report DCE line speed and error correction method xxx arbitrary letters The following two types of messages are accepted CONNECT 14400 No error correction CONNECT 14400 xxx...

Page 48: ...tachable 17 DIAL 46 DIFF 21 22 differential 18 DIFFERENTIAL 11 digital I O 29 digital inputs 30 digital outputs 33 division 12 downloading 6 D SUB 16 DTE connector 45 duration 8 E E 12 endless 9 erase...

Page 49: ...ding time 9 relay coils 29 relay outputs 29 Reset mode 31 resistance 37 resolution 13 retain data 9 RING 46 RS 232 26 RTC 5 RTD 38 S S 12 14 screw terminal 15 screw terminals 17 self heating 39 shunt...

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