Alan Case
Lifetime Supporting Member
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
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