Thermocouple module 1734-IT2I

tjntjntjn · Sep 18, 2015

Hi everyone,

I'm trying to set up a thermocouple module 1734-IT2I and am getting differential in the temperature reading. What I mean is:

I'm getting from thermocouple 350 counts what gives me 16.6 degrees Celsius (25 counts equals 1 degree) but the real temperature in the room when I work is 22 degrees. What am I doing wrong? Why am I getting different readings?

Thanks

Mickey · Sep 18, 2015

Proper theremocouple type configured? Cold junction compensation terminal block installed and configured ( enabled/disabled)?

http://literature.rockwellautomation.com/idc/groups/literature/documents/in/1734-in583_-en-p.pdf

https://www.google.com/url?sa=t&rct...-e.pdf&usg=AFQjCNEC97iC_lLCigNOljVufjSZL5_UOQ

tjntjntjn · Sep 18, 2015

I've red this literature.

I have thermocouple type J and that's what I set in the module configuration. The module is installed on 1734-MB mounting base with 1734-TBCJC terminal block which I believe has built in CJC. Right now I have CJC disabled. However when I turn the CJC ON the value of "channel 1 data.0" (I have my thermocouple in channel 0) increases from 350 to over 800 (with CJC offset set to default 70 degrees). That doesn't make even more sense cause 800 divided by 21 gives 38 degrees Celsius.

Does the terminal block 1734-TBCJC really have CJC built in or does it have to be the 1734-CJCRTB?

tjntjntjn · Sep 21, 2015

Anybody any ideas, please?

Midwest Maverick · Sep 21, 2015

This falls into Mr. Obvious category. But did you use the proper thermocouple wire? You can't just use copper wire. I wired up a thermocouple that way the first time I installed one and got odd readings similar to what you are getting.

tjntjntjn · Sep 21, 2015

Yes, I did use proper thermocouple wire.

danatomega · Sep 21, 2015

Along the obvious line: did you terminate the wires between the thermocouple and the module? You can't just use any old terminals, they must be for the thermocouple type.

tjntjntjn · Sep 21, 2015

I'am using the right terminal.
What do you mean by "did you terminate wires"?

danatomega · Sep 21, 2015

tjntjntjn said:
I'am using the right terminal.
What do you mean by "did you terminate wires"?

meaning :
"did you use terminals between the thermocouple and module?"

NetNathan · Sep 21, 2015

Tc positive and negative wiring not reversed any where? A double reverse will show this size of error.
Red is negative.

Are you sure you are looking at counts or are you seeing temperature? Usually the AB TC module converts the input to temperature.....ie 800 = 80.0 Deg.

tjntjntjn · Sep 21, 2015

danatomega said:
meaning :
"did you use terminals between the thermocouple and module?"

No, the thermocouple connects the probe and the module without any terminals between.

tjntjntjn · Sep 21, 2015

NetNathan said:
Tc positive and negative wiring not reversed any where? A double reverse will show this size of error.
Red is negative.

Are you sure you are looking at counts or are you seeing temperature? Usually the AB TC module converts the input to temperature.....ie 800 = 80.0 Deg.

I'm looking at the counts at channel data.0 and data.1 and according to AB installation manual 21 counts gives you 1 degree Celcius for type J thermocouple.
How can you at look/see temperature?

Wires are not reversed. I had them reversed at the bigenning and the counts would just go down while the temperature kept going up.

NetNathan · Sep 21, 2015

I am pretty sure you see temperature???? You ARE configured for C and not F?
In RSLogix...In the 1734-IT2I module properties box under "configuration", are you looking at "Celsius"?
You will need CJ enabled also for a correct reading.
The Cold Junction Offset should be at 0 unless you find you have to offset it due to calibration errors.

The module IS 21 counts per deg C across the range of -210 to 1200 C, but I still think you are already looking at temperature.

rkukl · Sep 21, 2015

I too struggled with this a while ago

The terminal base required is 1734-TBCJC

this is what BIT me wrong terminal base

tjntjntjn · Sep 21, 2015

rkukl said:
I too struggled with this a while ago

The terminal base required is 1734-TBCJC

this is what BIT me wrong terminal base

That's the terminal I'm using

Thermocouple module 1734-IT2I

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