Greetings wwcoop,
with the PLC-5, there are two basic ways to set up the PID ...
(1) the old way (and there are still tons of these in use today) uses a 23-word integer-style control block (example: N7:100 through and including N7:122) ... with this type of PID, you will not be able to enter “floating point” numbers for any of the settings ... but that’s ok ...
(2) the new PD-type control block (only available with “enhanced” PLC-5 models) will require you to create a new data file (example: PD9:0) to contain the PID control structure ... this method allows “floating point” entries and more flexible settings ... we’ll eventually learn about this method too if you want to go that far ...
if you’re trying to make your experience as portable as possible, then I recommend that you start with the older integer-type control and we’ll go from there ...
I recommend that you “simulate” a 1771-IFE analog input module with a 4-20mA input ... you don’t need to actually program in the “simulated” module - but you must have a realistic address for the Process Variable (PV) ... I suggest N7:54 ...
you need to specify the minimum (4mA) temperature reading for your temperature transmitter ... for right now I’ll assume (gosh I hate that word) that you’ll be using 0 degrees F. ... this will correspond to a data reading of 0 at the PV ...
you also need to specify the maximum (20mA) temperature reading for your temperature transmitter ... for right now I’ll assume (I still hate that word) that you’ll be using 250 degrees F. ... this will correspond to a data reading of 4095 at the PV ......
I recommend that you “simulate” a 1771-OFE2 analog output module with a 4-20mA output ... you don’t need to actually program in the “simulated” module - but you must have a realistic address for the Control Output (CV) ... I suggest N7:75 ...
this setup means that a CV signal of 0 at N7:75 will generate an output of 4mA to the control valve in the field ... also ... a CV signal of 4095 at N7:75 will generate an output of 20mA to the control valve in the field ... for now we’ll assume (man that word is killing me) that 4mA will close the steam valve completely ... and that 20mA will open the valve completely ...
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the yellow highlighted settings temporarily put the PID into the “Set Output Mode” for testing the input and output signals ... this is basically one type of “manual” control mode ... with the settings I’ve given, the CV at N7:75 should go to a steady value of 1024 (4095 times 25% equals 1024) ... then you should be able to increase and decrease the CV by changing the “Set Output Value” ... if your “simulator” is working correctly, the PV should start to increase and decrease as you manually open and close the valve ... specifically, the value at N7:54 should increase and decrease between 0 and 4095 ... and the “Scaled PV Value” on the PID setup screen should increase and decrease between 0 and 250 degrees ...
suggested plan of attack:
(1) let us know when you’ve got this much working ...
(2) post your current .RSP program file ...
(3) ask specific questions about specific entries that have you puzzled ... be sure to tell us what you’ve already tried ... and what results you expected ... and what results you saw ... and why those results have you puzzled ...
you can find the official description of the PID instruction as used in the PLC-5 in Chapter 14 of:
The PLC-5 Instruction Set Reference Manual
so ... are we having fun yet? ...
in your first post you said:
now in the picture above you have almost all of the settings involved for one very popular method of setting up a PID ... so which of these settings are giving you the most trouble? ... we’re ready to help ... just tell us where it hurts ...