Greetings Kron,
here’s just a little bit more detail ... suppose that your operator has a potentiometer on his control board ... suppose that the potentiometer puts out a “plain vanilla” range of analog values from 0 through 4095 ... suppose that the value from the potentiometer’s channel lands at N7:55 ... the value would be placed there by a BTR (Block Transfer Read) instruction as mentioned in Ken’s post ...
suppose that when you programmed the PID instruction, you entered in the address N7:55 for the “Tieback” setting ...
next we need to know how you’ve set up your PID instruction ... specifically, did you use an N-type control block? ... or did you use a PD-type control block? ...
for the N-type (oldie but goodie) control block, you would now go into the PID and put the “Mode” setting to “Manual” ... the PID’s output (the CV) will now track the Tieback value ... this will allow the operator to turn the potentiometer up and down and manually control the system ...
or ...
for the PD-type (new and improved) control block, you would now go into the PID and put the “A/M Station Mode” setting to “Manual” ... the PID’s output (the CV) will now track the Tieback value ... once again, this will allow the operator to turn the potentiometer up and down and manually control the system ...
in many systems the Tieback feature is not used ... in those cases a value of “0” (zero) is entered for the Tieback setting ... this basically just turns the Tieback feature off ...
going further ... another source of confusion is the OTHER manual mode ... (yes, there is another one beside the Tieback) ...
for the older N-type control block, you could go into the PID and put the “Set Output Mode” setting to “Yes” ... the PID’s output (the CV) will now track the “Set Output Value %” setting ...
or ...
for the newer PD-type control block, you could go into the PID and put the “Software A/M Mode” setting to “SW Manual” ... the PID’s output (the CV) will now track the “Output %” setting ...
and one more thing ... if BOTH manual modes are enabled at the same time, the “Tieback” (also known as the “A/M Station Mode”) will win ... specifically, it will override the “Set Output Mode” (also known as the “Software A/M Mode” ...
that should be enough information to get you on the right track ... the best way to nail this type of stuff down is to experiment with a SAFE system ...