On/ off state detection with serial device

[Dennis_Knutson]

If that 9 pin connector is used for the instrument the op is aking about, not only is a com port on the pc incorrect, but there is no method for reading status. All pins are for control. Manual control would have to be disabled.

[JoMu2015]

Thank you. I think that means I have to attack this problem in a different way but this answer does help.

[Basil-B]

Hi JoMu2015,

I am not clear from the history of the thread whether or not we know how the serial instrument represents the pump being off. Is there a specific query command that you can send whose response is whether or not the pump is on? Another potential issue is that, as someone described earlier, having a heating element controlled in software could be dangerous if the software crashes.