FP-TC-120 : Channel 0 gives bad readings after reaching 100F

[lampron]

I am using a FP-1001 module to communicate with 5 FP-TC-120 modules. The problem I have is that channel 0 on the first three FP-TC-120 modules goes out of range at 100F. All of the other channels are working fine.

I have checked the configuration settings in MAX and channel 0 is set up the same as the rest. I also checked the readings using Tag Monitor and when the value is below 0F the quality column says "good" but as soon as it reaches 100F it says "limit exceeded".

I have tried swapping FP-TC-120 modules as well as the FP-TB-3 bases with no luck. The firmware is up to date, Rev. 0030. There are no other modules connected to the FP-1001.

Any ideas?

[Aaron_G]

What type of thermocouples are you using? How are they mounted? The [c]FP-TC-120 modules are not designed for a large amount of channel to channel common mode voltage. If several channels are biased with more common mode voltage than the others, you may observe this type of behavior. One solution is to re-arrange the thermocouples so that thermocouples that are at the same potential are on the same module. Also, make sure that you do not wire the V & C terminals from one FP-TC-120 to the next.

Regards,
Aaron

[lampron]

Thanks for your response. The problem actually turned out to be quite simple. The "coerce range" setting in the tag configuration was checked off for a range of 0 to 100, so the TCs read fine up to that magic number.

Thanks again,
Ray