Part 2

582 Example 3497A ConfigurationsEXAMPLE 7HARDWARE COMPENSATEDTHERMOCOUPLE MEASUREMENTSDESCRIPTIONThe 20-Channel Relay Multiplexer with Thermocouple Compensation assembly (Option020) can be used to determine the temperature of B,E,J,K,R,S and T type ther-mocouples. The assembly can be configured for hardware compensation or softwarecompensation. This example shows how the temperatures of up to 20 J-type thermocouplescan be determined by using the Option 020 assembly and standard lookup(N.B.S.) voltage-to-temperature tables.PROCEDUREFigure 192 shows a simplified block diagram and connection diagram to measure thevoltage outputs from up to 20 thermocouples connected to an Option 020 assemblyin slot 0. Since hardware compensation is to be used, only ONE type of thermocouplecan be used per assembly (i. e., you can't mix J and K types on an assembly, etc.).For this example, we'll scan the 20 channels and measure the voltage on each chan-nel. Since the assembly is in slot 0, channel numbers are 0 to 19. Then, we canuse a standard lookup table to convert the measured voltages to equivalenttemperatures in degrees F.CONFIGURATIONFigure 193 shows how to configure the Option 020 terminal card for hardware compensationof J-type thermocouples. Since the Option 020 assembly is factory configuredfor software compensation, the jumper shown in Figure 193 must be removedwhen R120 and RlOO are installed.After configuring the terminal card, check to make sure that the TIC COMP jumperon the relay card is in the TIC COMP position. Then, connect thermocouples asshown in Figure 193. Note the various ways to connect thermocouples, dependingon the type.Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com