Analogue IO cards


#1

Why we are using different analog input cards for RTD and T/C instead of normal Analog input cards…?


#2

Normal analog I/p is in the range of 0 to 10V or 4-20ma signals.For that type of signals normal analog input cards are used. But RTD ouput are in resistance variation and Thermocouples output are in the range of mv which require special conditioning before processing. For this type of signals , we are using special type of analog input cards. Example for Honeywell DCS, For normal analog input using HLAI cards(High Level Analog Input) and for RTD and T/C using LLAI cards(Low level Analog Input).


#3

Thank you Omega

does it compulsory to use temperature cards instead of normal analog cards. if yes, what will we do for compact or fixed controllers then?