I find a problem
as attach jpg
PID num 1 & PID num 2 are all the same , only diff with Time
PID num 1 Time= Min
PID num 3 Time= Hour
Q1:
as beginning ,PID1 & PID3 output value are running correct
but after one or two day ,the PID1 output seem to sluggish … dead …
as mark in the attach jpg
PID1 Set Value 10.0 << Input 16.9 , but the output 0% is un reasonable
(PID3 is OK)
Q2:
is there any basic language command can set the Time , Der , Bias in the PID
loop
The symptoms you describe could be because of ‘reset windup’ which is where the I term gets large and takes a long time to unwind. I would set both the I term and the Derivative terms to zero and work on getting the system working basically OK with just the P term. Once you have it working basically then you can introduce a little I term. Generally the ‘Hours’ setting will make the system respond very slowly. And my personal preference for the derivative term is to just leave it at zero, it complicates things unnecessarily for simple HVAC type applications.
There are commands to read & write to the PID settings, hit the F1 help key to bring up the help system and it should show up in a search.
