84 Thermocouples

There are a number of options for reading 84 thermocouples on a system I am proposing to upgrade but it can get costly and take up a lot of room. PLC platform has not been chosen yet. I have seen some info on the Red Lion CSTC8000. Has anyone used these and are there any thoughts on them, or thoughts on any other option for reading a large number of T/Cs? Momentum max 4 per card, SLC max 8, Compact max 6, Control max 8 & $$ Thanks!!

If the temperatures are not changing fast you could possibly use something like this multiplexer.

http://www.omega.com/pptst/CIO-EXP16-32.html

You will need 4 outputs to select between the 16 channels to read into 1 analog input in your PLC. Then you just keep cycling through the signals you need at the rate you want them to update. A little more work in the program but a boat load cheaper in the hardware if you wan live with only periodic updates. That will depend a lot on the process you are monitoring.

3 of the 32 point version will cover your 84 inputs.

I have used the Terminator I/O T1F-14THM from Automationdirect in the past for thermocouples. 14 inputs and the Do-more processor can be used right in the stack.

Sixnet "EtherTRAK-2" (owned by Red Lion) makes a 16pt isolated TC input module that is nice. You can talk to them with Modbus TCP or use their software.

http://www.redlion.net/product/ethertrak-2-io-module-16-isolated-thermocouple-inputs

We've used these quite a bit. Available in Ethernet/IP or Modbus/TCP, webserver configurable, good isolation for noise. The only thing I don't like is the T/C type selection is in groups of 3 for the 6-channel units. Pricing is pretty reasonable.

https://www.acromag.com/catalog/250...modules/analog-io/busworks-900en-series/965en

a cheap solution can be to use converters to a 4/20 mA signal, some resistors of 250 ohm and a 48 relais for each channel. this all gives one analog channel (as this is pricy.)