Part 2

586 Example 3497A ConfigurationsEXAMPLE 8SOFTWARE COMPENSATEDTHERMOCOUPLE MEASUREMENT'SDESCRIPTIONThe 20 Channel Relay Multiplexer assembly with Thermocouple Compensation (Option020) can be used to determine the temperature of B,E,J,K,R,S and T type thermocouples.The assembly can be configured for hardware compensation or softwarecompensation. This example shows how the temperatures of up to 19 J, K, E, Rand/or S-type thermocouples can be directly measured by using the Option 020assembly.PROCEDUREFigure 194 shows a simplified block diagram and connection diagram to measure thevoltage outputs from up to 19 thermocouples connected to an Option 020 assemblyin slot 0. Since software compensation is to be used, any mixture of thermocouplescan be used per assembly (i. e., you can mix J and K types on an assembly, etc.).For this example, we'll scan the 19 channels and measure the voltage on each channel.Since the assembly is in slot 0, channel numbers are 0 to 19. Between eachchannel measurement, we'll measure the reference voltage on channel 19 (B9). Theprocedure is as follows:1. Measure the temperature transducer voltage from channel 19 (channel B9) andcompute the terminal junction's temperature in deg C (2.5V at 25 deg C with 100mV/deg C.).2. Convert the terminal junction's temperature to a thermocouple voltage. The convertedtemperature is dependent on the type of thermocouple being measured.3. Measure the voltage produced on a channel by the thermocouple.4. Add the reference voltage of step 2 to the voltage in step 3 for an icepointreference voltage and then convert this to degrees C and degrees F.Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com