Failed drive PID S71200

Pegaia

Hi,

first point: pay attention to don't use wrong data types: Setpoint is in float. Process value is either float or integer (0-27648).
Take also a look at /tf/WW/en/Posts/33957#top

primus 1

Hello

I have a couple of questions.

1. What tempeature range are we talking, type of thermocouple?
2. How are you determining you are under temp, from plc or secondary source?
3. And is it a constant 212 degrees below setpoint at a variable range of setpoints?
4. What type of output analog or digital?

Tom

Bettino

I am facing some problems setting up PID CPU Block S71200 (1214DCDCDC).
In fact the block works, but with a difference of 212 ° F between the variable and process variable Set Point.This happens even after making the whole process of tuning the module start to move automatically and the values ​​are saved on the CPU. What would be the way to solve this failure?



Thaks.

huggy_d1

Bettino

I am facing some problems setting up PID CPU Block S71200 (1214DCDCDC).
In fact the block works, but with a difference of 212 ° F between the variable and process variable Set Point.This happens even after making the whole process of tuning the module start to move automatically and the values ​​are saved on the CPU. What would be the way to solve this failure?



Thaks.

212F = 100C Makes me think something could be wrong with the units on the PLC TC input.

For me, the PLC input input for TCs is the raw temperature x 10, so 212 F would appear as 2120.

If your your PID is set to control a heater or a chiller valve, and your set point is off by 212F, can you simply offset your process variable by 212 before passing it on to the PID block?

Maybe you can just scale the TC input to 0.0-1.0 and have your set point scaled to 0.0-1.0. Perhaps then your PID set point and process variables will be compatible and forced to be operating with the same range/scale.

Just a thought.