Hello Rayshan,

Is it possible that the PID controller was accidentally reset? It sounds like you need to adjust the controller gain. You could make a record of the current settings and then perform the autotune function (most manufacturers recommend performing twice).

If that fails, a good (manual) PID tuning guide:

http://sts.bwk.tue.nl/7y500/readers/.%5CInstellingenRegelaars_ExtraStof.pdf

I hope this helps, best of luck and let us know if you fix the issue!

Hello Rayshan,

the possibility described above by Jules is definitely something to consider. Maybe within these 2 months the controller has been reset to its default tuning values or even turned manual for some reason. I suggest you double check the tuning parameters and retune your controller.

Best of luck!

Hello Rayshan,

You need to check the parameters of controllers and tune it again if necessary.

Best of luck!

It could be possible that during your absence a power failure occurred and the controller lost its configuration and its ability to control the temperature. Also, check the connections since a loose wire from the temperature feedback signal could explain the problem. If the controller is not adjusting the temperature and the connections are good, then, most likely the integral and proportional gain were reset to zero or to a very low value; otherwise, the controller should be adjusting the output.

Hope this helps.

You do not write whether the real temperaturę is circa 82,3C or not. I assume that it is.

There is possible a lot of reasons:

1) Temperature sensor fault or sensor disconnection. In this case controller may assume that controlled temperature  is below setpoint and hence  saturates the controller output.

2) The temperature feedback is positive.

3) Controller output offset (if available) is set to 52.3C

4) Controller output fault - shortage in electronic part

5) Internal fault of controller

6) Bug in controller software

7) Control system is unstable and oscillates between on and off states. In this case:

a) switch off Integral part. Please note, that there are two kinds of controllesr. In some of them swithing off integral part means - set maximal integrating time constant Ti. In some of them  you should set Ti=OFF.

b) switch off derivative part. Td=0s

c) set proportional action Kp=1..2 (Xp=0.5...2)

d) set output offset to 0 ( if any)

e) set input offset to 0 (if any).

f) reset controller

Restart the   process. The steady state error will be different then 0, but not 50.3C. If you will observe relative small steady state error then  adjust appropriately Kp, Ti, and ew. Td. 

I would mail/phone to manufacturer or check their site for FAQ section. 

Dear Colleagues,

Sorry for opening an old topic.

However I have faced the problem with STC200, INSTEC controller.

The temperature is shown without 0.1 C degree precision. The stage warms up higher than temperature set but does not cool down.

Could you please tell where I can find the resetting procedure or default parameters?

Thank you.