1762-if2of2

Alan Case

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Join Date
Apr 2002
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Wagga Wagga
Posts
1,268
Hi.
Just wondering if I am doing something wrong or I have misread/misunderstood the manuals
I have just finished commissioning a 1762-IF2OF2 (analog combo card) connected to a MLX1100. I set the card for 4-20mA scaled for PID and according to the manual instructions the raw values are 0 - 16380. Using SCP on the analog input the engineering values obtained were out. After much head scratching and trawling the knowledge base I found a doc that details the card is 4ma = 3200 and 20mA = 15600. 21mA = 16380. So using these values as the max/min in the SCP allows me to get the correct engineering units.
But I also wish to use the raw input channel in a PID loop (You would think this possible and the reason why you could scale the input this way) The PID block expects the raw value to be 0 - 16383 not 3200 to 15600 so the PID values are off.
I have to use another SCP to convert the 3200 - 15600 into an integer of range 0 - 16383 and use this integer in the PID block.
Now every thing reads correct but what a waste of time; why is the manual not correct?
Regards Alan Case
 
Also...this going completely off of memory, this module is a 0 to 21 mA analog input. So a raw scaling of 4-20 with your SCP would be 6240 to 31200.

I think the PID is half of that or 0 to 21 mA is 0 to 16380 so a 4-20 SCP would be 3120 to 15600.

Like I said this is completely off of memory but Ron Beaufort will be by in a few hours to correct me if I'm wrong
 
By default the dip switches are for current.

Here is a compilation of the modules manual

Manual.JPG


The values of 3200 to 15600 are correct but this module does not work with the PID block using just the analog input unless I am missing something.
Regards Alan
 
Last edited:
After a lot more searching I found a knowledge base doc that
describes this as a "wrinkle"
Knowledge base doc ID 41224.

Why can't the docs that come with the card detail this.

Regards Alan Case
 

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