Thanks for all the info from everyone, I appreciate it. I come from an IT background and am just learning ladder logic. Have a little bit of instrumentation knowledge, have worked with various HMI's, Bristol controllers etc so I think I can pick it up. I just want to make sure I am taking the right approach to the code, and unfortunately I was "volunteered" for this project and told we need it done yesterday.
Here is more background of what I am trying to do:
Using an AB Enhanced PLC-5/20 16384 mem. and AB 1794 remote I/O
I am trying to do a ratio control based on flow. FI-1067 should be 10% of FI-501. So if FI-501 is 2000 I want FI-1067 to flow 200. I have a flow control valve to control, FV-1067, for this purpose.
I need to be able to do the following:
Be able to run FV-1067 in Manual and drive the output
Turn Ratio control, as stated above, ON and OFF
Be able to run FV-1067 in Automatic and manual input a Setpoint
I guess my main questions are how to set up the "manual" code. When the PID instruction bit is set manual, where does the output get driven from is this separate coding or will the PID instruc handle this?
What is the right code to turn the PID bit (word 1 bit 1) on/off when I want the valve to be manual/auto?
What value should go in the tieback word?
Attached is my coding attempt, does this look proper?
I appreciate any ideas, comments, nudges
Thanks!