How do I control and tune a Omega Platinum temperature controller with labview?

[Pt2016]

I'm using a heating mantle as the heating source, and an omega type J thermal couple.

The autotune is generally successful with DONE at the end, with PID value of P ~ 20, I close to 0, and D of ~ 300.

For the PID control, I set as reverse, which corresponding to heating, and the cycle time was set as 1 second.

I consulted muliple sources on control engineering, especially topics related to PID. Even fitting with matlab pidTuner are also tried, however, no luck up to now.

Please let me know what could be the right route towards proper PID values. Thanks.

[fransv1963]

Reverse is indeed the correct/default setting.

I'm currently using 5 seconds as cycle time (which I believe is the default).

Decreasing the cycle time should improve the "fine" control.

To me it's bizarre that you don't have a control signal similar to what I have (either no VAC applied or VAC applied during a % of the 5 seconds cycle).

What is the control signal you are showing?

My other humble advice would be to start from the auto tune settings and look at the effect of manually adjusting the P value in both directions (e.g. divide by 2 and multiply by 2) and to verify how this impacts your overshoot behaviour (larger P and I values are mainly used to reduce the steady-state error, while D is mainly used to stabilize the control loop).

[Pt2016]

I think you made a quite right point on the control. We have the pretty much same model, you have model number of CN16PT-330, I'm using CN8DPT-305. We all try to control heating with SPDT Mechanical Relay, which should result with similar control signal.

The signal I showed is the one I recorded with platinum configurator, the same as you did. Could this be the possible reason why I'm struggling with the control?

I think we could save the configuration parameters with the platinum configurator, if you don't mind, could you please upload your Platinum_Configurator file? First, please go to platinum monitor_tools_options, then select all the parameters in the File Save options. Then, File_Save should have a copy of the detailed configurations. I'd like to compare yours with mine to see any differences.

As for tuning the PID values, I tried auto-tuning, then manually trial-and-errors for numerous times, basically, pretty much no logic could be appreciated. It's really confusing to me.

Could you please provide further ideas and suggestions? The tuning process and control engineering is really something to me. Thanks.

[fransv1963]

Will do so when I'm at the office.

What heater are you using?

I'm using either the SRFG-1212/2-230V or SRFG-1218/2-230V silicone rubber heater.

Do you run the latest firmware/software?

[Pt2016]

Thanks a lot for kindly providing me the parameters, which should greatly faciliate me troubleshooting those problems.

As for the heating device, I'm using Glas-col 100A 0396 heating mantle.

I didn't try update firmware, since I'm not sure which verison of firmware my temp controller is at. As for the software, I just checked on the omega ftp site, everything is properly updated. Thanks.

[fransv1963]

Here's the file with the configuration data.

[Pt2016]

Thanks a lot for uploading your configuration file. I compared yours with mine side by side, barely any diffrence. Anyway, I'll try to dig deeper to see if those trivial changes couldl bring magic moments to my temperature controller.

Your further suggestions and comments are more than welcomed.

[fransv1963]

There is not much more to say from my side, sorry.

I would mainly focus on why the control signal is that much different than mine given the fact that you use the same SPDT switch and that your heat mantle is also purely resistive (had a quick look at the website).

Adaptive Control is disabled? If not, I would disable it.

Good luck !