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Thermocouple reading V350-35-TA24


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I have a problem.

I have 2 same main boards of the PLC V350-35-TA24 with same HW and SW configuration, but there is a problem. 1 of the PLC is reading the Thermocouple temperature and the other reading constantly -0.1C.

I've passed the configuration a lot of times, the boards REVs and etc. it all the same....

there is probably something in the way tha confusing the Thermocouple reading in the main board but i can't find it. Is anyone can help me by providing me a solution or schematics or where the thermocouple is connected to the main board and rhough what devices it going.

Thanks in advance.

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  • 2 weeks later...


0.1C difference between 2 OPLCs is not a problem.

From Datasheet:

Resolution is 0.1 C.

Cold junction compensation error ±1.5°C maximum.

Full-scale error ±0.4%

Linearity error ±0.04%

Warm-up time ½ hour typically, ±1°C repeatability

Everything is in range.

So why do you panic and require schematics?

It seems useless. Isn't it?

My advice is to use it as-is. I see no problem in your configuration.


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  • MVP 2014

It sounds like one of your thermocouples always reads -0.1C regardless of temperature.

As Alex suggests, the scehamtic is not going to tell you much.

I would check:

* swap thermocouples to ensure they are both working

* ensure the thermocouple is connected with the correct polarity

* configure another thermocouple input on the same PLC.

The most likely problem is a faulty probe, incorrect/faulty wiring or configuration error. If those can be conclusively eliminated, then perhaps there is a faulty input on the PLC, but that is the least likely, based on my experience.

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