1756-it6

I am having a problem with 7 Allen Bradley 1756-IT6 thermocouple input cards. I am using the J type thermocouple inputs for the card. I also am using the cold junction sensor. I have 1 good card that is giving me the correct readings. I have 6 cards that are not. All the 6 bad cards are exactly 110 degrees off. I am not sure if the cards have bad parts or if they need to be calibrated. I am trying to calibrate the cards following the procedure from the manual. The problem I am having is that when I try to select calibration in the property menu I get the following error "The module can not be found. The path specified was invalid". And it will not let me start calibration. I have the major and minor revisions set properly so I am not sure what the problem is. Please help. May I also note that all the cards work properly when I use the milivolt input instead of the thermocouple. I am confused!!!

Welcome to the forum, It seems to be that your problem is configuration, plese post a pic showing how you set up your cards.

If you swap a "Bad" card, with the one "Good" card, are the "Good" readings still good? If so, you have either a configuration issue, or a wiring issue on the "Bad" cards.

You can hot-swap (provided it won't hurt your process) with Logix.

Thanks for your help. What I have is just the power supply, the 1756-l55 processor in slot 0 and the 1756-it6i/a in slot 1. All I am trying to do in test all the inputs on the card. With the one good card I have the properties set under configuration the exact same as the bad cards. I am using the same program to test the good and the bad cards. So this is leading me to believe it's not a configuration problem. I am also using the same wiring connector for all the cards. I

In the picture the card is set for slot 9. I was trying different slots.

110 deg is something more then just a calibration. Check wiring for proper polarity. All wiring, not just at the card.

http://www.omega.com/techref/thermcolorcodes.html

I know that it's not the thermocouple wiring. Because the one good unit works fine. But I am still having trouble trying to calibrate the units.

Are you wiring TC extension wire's directly to the TC Card input wiring arm? or are there other junctions in between?

On the 'Bad' cards, remove all wiring, and connect them one at a time, are the individual channels still bad?

How about just connecting one T/C at a time, locally directly to the 'Bad' modules.

What do the CJC devices read for temperatures? (Module:Slot:I.CJData)

jtorres2 said:

I have 1 good card that is giving me the correct readings. I have 6 cards that are not. All the 6 bad cards are exactly 110 degrees off. !!!

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Wait, wait, please tell us how you are observing your temperature being measured, the pic of your config is confuse, your Engineering values should not be the same as your millivolts values, if that is true you have to use a table to convert from mV to Degrees. Your engineering values must be the minumun and maximum of values in degrees F of your type J thermocouple, this way you can monitor your temperature thru rslogix or a scada system.

widelto said:

Wait, wait, please tell us how you are observing your temperature being measured, the pic of your config is confuse, your Engineering values should not be the same as your millivolts values, if that is true you have to use a table to convert from mV to Degrees. Your engineering values must be the minumun and maximum of values in degrees F of your type J thermocouple, this way you can monitor your temperature thru rslogix or a scada system.

Click to expand...

widelto,

Those are default values and should be ok. At least thats my reading of it. See pic below, note the important message.

Yes I am using the default values for the j type thermocouple.