I am trying to set up an Sestos D1S temperature controller. Initially, just to see if it works at all, I am trying to use it to control the temperature of my kettle. I've wired it all up correctly so that it can switch the kettle on and off, and the temperature probe is in the kettle. The temperature reading on the front is correct, but the device seems to be impossible to set up.
I have tried autotuning, manual tuning, and simple manual mode. None of thes has worked properly. The only thing which does work is On/Off mode, although it seems to only switch off about 2 seconds after the temperature has gone past the set point.
How do I set up the time period?
Since the kettle heats up very quickly, the time period should be very short, and preferably the duty cycle kept low. Se I set the Ctl (Control Period) to 1, for 1 second. I assumed that I would see the output switching on and off at 1Hz, but I do not. I also set the oPH to 50, meaning that it should have a maximum 50% duty cycle. However, the output stays on for many seconds.
How do I set the PID valued? According to the manual:
M50 = Integral
P = Differential
t = Hysteresis Time
Can this really be correct? Where is the Proportional setting?
How do I get it to auto tune? I followed the manual and managed to make it flash 'At', which I think means it's Autotuning. However, the temperature fluctuated wildly, and finally settled, oscillating between 53ºC and 60ºC, even though the set point was 50ºC.
Added: I am using the following settings
dF 0.3 (Hysteresis) Ctrl 3 (PID mode) M50 0 (Integral) P 1000 (Proportional?) t 0 (Derivative?) Ctl 1 (Control Period: 1 second) oP1 0 (Output method: Time Duty) oPL 0 (Output minimum: 0%) oPH 50 (Output minimum: 50%) run 1 (Automatic)
With Ctl at 3 (3 second period) and the output duty at 50% (display reads A 50) I an see that the output comes on for 35 seconds, then goes off for 35 seconds. This is a period of 70 seconds.
With Ctl at 0 (0.5 second period according to the instuctions) the period is still 70 seconds.
So it looks like the control period is stuck at 70 seconds. Flicking through the settings, none of the numbers are set to 70 (or 35 or 140). So I don't think there's another setting which is controlling the period.
Ctl Period 40 = 40s 20 = 20s 10 = 10s 8 = 8s 6 = 8s 4 = 8s 3 = 8s 2 = 70s 1 = 70s 0 = 70s
I set P=2, I=0, D=0, Max output = 50%, and set the setpoint to 70ºC. I watched the output duty as the temperature rose slowly to 69ºC. At that point, the output duty slowly began to fall, until at 70ºC it was still at 42%. It finally settled at 79.4ºC with an output duty of 4%. This really sounds like a fault in the control.