Phidgets Forums

Posted: **Mon Jun 04, 2018 8:31 am**

I'm attempting to create a class that enables pressure sensing using the Phidgets Interface Kit and a few different pressure sensors.

When I go to open the channel, I keep getting the error: Invalid Argument

Code: Select all

prc = Phidget_openWaitForAttachment((PhidgetHandle)sensors[0].ch, 5000);
			if (prc != 0)
			{
				std::cout << prc << std::endl;
				fprintf(stderr, "Runtime Error -> Attachment Failed: \n\t");
				DisplayError(prc);
			}

What are some of the things that could make the opening invalid? The Voltage Ratio Input Example works, however I'm not sure what could be missing to cause this error. I don't get any errors when setting the parameters. I've attached my .cpp as it's a bit big to show inline.

Any help would be greatly appreciated

PressureSensor.cpp: (11.2 KiB) Downloaded 833 times

Posted: **Tue Jun 05, 2018 5:09 am**

Solved it. Apparently attempting to create the channel handle using:

Code: Select all

this->prc = PhidgetVoltageRatioInput_create(&this->ch);

doesn't actually work if it is placed in the constructor. Moved it out to a different class member and it works a treat.

I would be grateful if someone could shed some light on this, as running functions in a constructor is usually quite alright.

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