thermocouple analog input for plc

hello

i am trying to setup a 4-20 analog input signal for a plc, i am using a jenco 77a type j thermocouple converter with a 4-20ma output (temperature range 32-532). for my zero input temperature, aprox 40 degrees, i am able to set the zero output value to 4ma. i read that the span should be the difference between the high and low range and in this case sould be 20-4=16ma,but when i try to set the span on the converter it max out at 6.3ma. my high temperature value is aprox 80 degrees. i want to feed this signal to a plc analog input to display temperature value on an hmi.

thanks

You must scale the analog input to match the limits of the device. 4ma = 32 and 20ma = 532. The range of the values you are actually measuring have nothing to do with scaling the PLC.

If you are trying to calibrate your converter you are going to have cool the thermocouple to 32 deg and adjust the zero for 4ma. Then heat the thermocouple to 532 deg and adjust the span for 20ma.

If you have heated the thermocouple to 80 deg with a span of 32-532 (4-20ma) then your milliamps should be about 5.54ma.

link to the manual if needed.

https://www.google.com/url?sa=t&rct...dTMl_zNnndiDu-jjXRbEehQ&bvm=bv.50768961,d.cGE

See attached for a useful tool. Courtesy of John Soltesz

Thanks Mickey for posting that chart, and likewise to John Soltez.
handy tool.

Great Chart MICKEY