SCC-2345 thermocouple malfunction

[wwalton13]

I'm running an SCC-2345 box with three TC-02 modules inside. I started having an issue where, in ambient air, one channel would read ~10deg F higher than the other two. If I unplugged that thermocouple one of the other channels would jump to the high temperature. I verified each thermocouple/extension cable I was using with handheld readers. Each reading was coming from a MAX virtual channel, mapped to the box, CJC set to built in.

Not sure what's happening/what could cause a box that had been working fine to start giving me grief like this. Anyone seen something similar? 

[LindyHop]

Hello wwalton,

Is this new behavior? Can you describe what you changed before you noticed the behavior? Can you also list where in the SCC-2345 you have the TC-02s placed?

[wwalton13]

Jonathan,

I had probably been running the thermocouples off the SCC-2345 for about four months before I saw any problems with it. I can't come up with any signficant changes that were made in that time either. The box was physically moved a handful of times, but nothing internal was changed, the connector it was attached to on the DAQ card hadn't changed.

The TC-02's are in Mod5, 6 and 8 in the SCC board. After noticing the issues I did try rearranging the TC modules to see if I just had an issue with one of the physical ports in the box, but that didn't seem to have any effect. If it matters, there are also four LP-02 modules in Mod1-4.

Thanks,

Will Walton

[LindyHop]

Hello wwalton13,

If you use just one TC-02 can you verify if it is reading the correct temperature? When you have all three and you say one is reading higher than the others, are two the correct temperature and one is right? Have you tried checking the DAQ card to ensure that it is working correct (Use a known voltage source to test the channels)? If you remake the virtual channels do you get the same behavior? Does anything happen if you remove the LP-02 modules? 

Do you have another computer and DAQ card you can test the hardware with so we can start narrowing down the possibilities? 

[14nnb1]

Hello friends,

I'm using an SCC-2345 box with two TC-01 modules inside.

I am reading temperature of a furnace with them.

The problem is:

1- None of the TC01 units read the temperature correctly.

2- Each of them shows different temperature. I double checked with a handy thermo reader. 

I also double cheked all wirings, changed the thermocouple wire. 

Nothing changed.

Based on what I read in your previous conversations, I noticed you had faced the similar problem.

Would you please advise me what should I do next?

Best regards,

Nima,

[14nnb1]

Please let me add that my two TC01 units are plugged in J7 and J8 slots.

By replacing them with each other, totally different magntudes is read. J7 shows different temperature compared with J8,

Bests,