Problems configuring Thermocouple input on M340

I am looking for help with the M340 thermocouple input module (ART0414) connected to a Telefast cold junction compensator (ABE-7CPA412 ) I am having a problem configuring the plc to get the correct scaling. We are using it with type J thermoucouples (-237 to 1359 deg F). We are using the Analog scaling block (AN_IN_SC) to do the scaling with the following inputs.
IN_MAX = 10000
IN_MIN = 0
OUT_MAX = 1359
OUT_MIN = -237
The output is off significantly.

What am I missing?

You don't need to do the scaling; the module will do it for you.

In Unitypro double click on the ART0414 module in the project browser window then you can select the T/C type and C or F from the configuration tab.

You also have to assign a tag to the relevant input word in the variables editor - that tag will then have the value of the input in 1/10th of a degree units - all scaling, filtering and CJC having been carried out automatically as configured.

This analog card seems to require a 2 wire RTD for external cold junction compensation, presumably because of the remote terminal connections.

If you don't have a CJ sensor wired to ch 0 it isn't clear what the controller's response will be - but you will have an offset error due to the temperature difference between terminal block and the freezing point of water.

The ABE-7CPA412 unit has internal CJC, you can use an external RTD instead but I can't imagine why you would need to.

Selection of external/internal CJC is via the ART module's configuration tab.

Well, I only know what I read.

It appears that the combination of the card and the Telefast device amounts to remote terminal connections.

Correctly done, CJ compensation would be done at the remote terminals, so the Telefast unit has the CJ sensor for doing so.

I always find the Modicon manuals can be ambiguous but on further reading

"For each block of 4 channels (channels 0 to 3 and channels 4 to 7), the external
compensation of the module is performed in the TELEFAST ABE-7CPA412
accessory. This device provides a voltage in mV corresponding to:
Voltage = (6.45 mV * T) + 509 mV (where T = temperature in °C).
The overall margin of error when using this device is reduced to 1.2°C in the -5°C to
+60°C temperature range.
It is possible to increase the precision of the compensation by using a 2/3-wires
Pt100 probe directly connected to channels 0 and 4 (only for the BMX ART0814)
on the module or connected to the TELEFAST terminal blocks. Channel 0 is thus
dedicated to the cold junction compensation of channels 1, 2 and 3. channel 4 is
thus dedicated to channels 4 to 7."

and

"NOTE: When the cabinet where the TELEFAST ABE-7CPA412 accessory is
located and powered up, wait at least 45mn to achieve full precision of the CJC
compensation. It is not necessary to wait 45 mn if the compensation is performed by
an external Pt100 probe.
When using the TELEFAST ABE-7CPA412’s cold junction compensation, in order
to make sure you achieve the indicated level of precision, the movement of air
around the TELEFAST ABE-7CPA412 must not exceed 0.1 m/s. Temperature
variations must not exceed 10°C/hour and the TELEFAST ABE-7CPA412 must be
placed at least 100mm away from all heat sources.
The TELEFAST ABE-7CPA412 can be operated from -40°C to +80°C external
temperature."

Well, I'd call your discovery equivalent to local CJ compensation at the remote terminals, with whatever the stated caveats are.

So his error probably isn't CJ error.

It would be nice to know what the error is versus what is expected.