In PhidgetVoltageRatioInput_setVoltageRatioChangeTrigger(), I tried setting the change to 0.0. So I would expect the PhidgetVoltageRatioInput_setOnVoltageRatioChangeHandler()'s function to be called somewhat regularly. It is only called once when the device is attached. Never again.

I'm doing this on Linux. So, unfortunately, no control panel. There could be if it had been written in a portable GUI. But there you have it. Having a second opinion would be great so I could eliminate hardware failure.

Also, can use SENSOR_TYPE_3130 as the sensor type if you want to get the value back in %RH instead of volts. I have set it to this, but I always get the same value in the change handler: 0.291900. The value should be between 5 and 95 with this sensor. And if setting the type should result in a repo...

Seems I got off on the wrong foot with the humidity sensor. Ignore my two previous posts. I am using one of these: https://www.phidgets.com/?tier=3&prodid=222 So, I should use the VoltageInput class. I have now done this via: PhidgetVoltageInput_create PhidgetVoltageInput_setOnVoltageChangeHandl...

After a change to the code, I see that the open does fail. It does the same for the sample HumiditySensor_Example C program. That program reports: INFO [_phidget22usb][2017-09-26T10:45:07]:Initializing libusb INFO [_phidget22usb][2017-09-26T10:45:07]:New Phidget found in PhidgetUSBBuildList: 2/10 IN...

Thanks for that info. I have the temperature gauge sorted. My gauge is the 1051. So there is just the thermocouple and the board. I am guessing the board is what used to be called ambient temperature. The 'easier' humidity gauge is not as obvious to me. I have it connected via the 1019 Interface Kit...

I am starting to update from phidgets 2.1.8 to the current phidget22. In many places I see that things look the same (just name differences). In other places, I don't find things in phidget22. For example, with the single probe temperature gauge, there used to be functions like: CPhidgetTemperatureS...