DTB Temperature Controller PV Unstable error

Good Morning and Happy Holidays, Digi-Key!

I am wondering if you can help me decipher the DTB4896RR technical manual. In our application, I would like to use this controller to provide temperature limiting functionality. Specifically, I have a thermocouple on the heating element and I don’t want the heating element temperature to exceed 800 °F. Normally, this will not be a problem. In an error condition, the temperature may climb. I am hoping I can use the DTB4896RR in control mode, even though it won’t have much control over the process.

I am hoping I can set the setpoint to 800 °F. When the heating element is on, it will likely settle around 500 °F. The DTB will constantly call for more heat, but its output relay will not be connected to anything that will provide heating. When the heating element temperature exceeds 800 °F, I need the DTB4806 to stop calling for heat and open it’s normally open relay that has been closed for quite a while.

What I think it is going to get it the way is the on the last page of the DTB4896RR data sheet: Error Status 0001H, PV unstable. Will this error condition flag if the controller notices it has no control of the temperature?

Best Regards,

That error message or the conditions that would trigger it do not seem well-defined in the document… Regardless, the device appears to have an on/off control mode which presumably disengages the more advanced PID functions and turns the unit into an over-educated thermostat. I’d expect that mode would work for the sort of backup monitoring function that you seem to be describing.

Hi Rick,

Happy New Year and thanks for replying. Would you mind if I contacted DTB to find out for sure?


Temperature controllers are used in a situation where we need a temperature to be in a stable condition. If the DTB temperature controller is showing the unstable error then it has to be fixed to find out the temperature changes against the set point.
As these are electronic devices you need to check the errors if there are in the microprocessor, battery, and other parts of the device.
Generally, these devices are set against an ideal set point irrespective of the environmental condition.
There are divided into types of controllers one if the open-loop controller and the other is closed-loop controller.

Open-loop controllers are the most basic type of controllers. They execute their job of heating or cooling irrespective of the output temperature. Whereas close-loop temperature is more organized and handles the temperature with extra observation. Here the output temperature is constantly measured and adjusted to maintain the constant value output at the desired set temperature.

In order to troubleshoot this PV unstable error, you have to identify which type of controller you are using?

Hi Sakshiverma,

Thanks for replying. We are thinking of using the DTB4896RR controller.