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# Thermocouple

## 11 posts in this topic

Hi wizards ive got a micrologix 1100 with a 1762 - ITV thermocouple expansion module on but im having trouble getting it to read the actual temp it a J type and is reading 1750 deg on I:4/0??

forgive me as im a newbie but after setting the parameters to J type in advanced config i thought it'd just be able to read the true temp. ive attached some screen shot of the logic and settings

any help would be awesome

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I'm pretty sure you to have to scale the raw value (1744 in your screenshot) to engineering units. I can't look for it now, but there should be a datasheet or user manual covering that module that gives the ranges, like 0-1000°F = 0-16000 counts or something like that (I just made those numbers up). You would then use a SCP instruction to convert your raw counts into degrees. You can also experiment with it if you know the actual temperature by just adjusting the parameters of the SCP instruction until you get a good reading. I would rather find the actual relationship between counts and degrees, though.

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It may have an implied decimal point - 1750 = 175.0 degrees.

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Yo have channel 0 configured for "Percent Value" which has an implied decimal point of 2 places, so your read is 17.5 % full scale.

You can change that to Engineering Unit X 1 to get a direct temperature reading.Or engineering units x 10 to get a direct temperature  reading with an implied decimal point to 1 place.

See pdf

rawdataformat.pdf

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Thanks guys but Mickey you are a star thats just what it was but its now reading 18 deg C which is great but id like it to read 18.5 with a decimal??

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Then use the "Engineering Units x 10"(data format), use a math instruction to divide the raw data by 10 with a destination of a floating point data type.

Edited by Mickey

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hi Mikey thanks once agin for the post ive got  Engineering Units x 10"(data format) that gives me a usable reading but if i divide it by 10 and put it on F8 itll read 1.8 if i store the raw data 18 deg on a f8 without dividing it gives me 18.0 but not 18.1, 18.2, 18.3 etc as the temps climbing it'll just go to 19 20 21 etc??

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Sorry, I should have said "Engineering Units x 1"( my bad).

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ive not got that option any ideas?

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I would expect "Engineering Units" to be equal to "Engineering Units x1".

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39 minutes ago, Joe E. said:

I would expect "Engineering Units" to be equal to "Engineering Units x1".

Yes