Hi Everyone,
I have an USB-6501 connected to several electro-mechanical relays through digital out which control several solenoid valves. I also have one digital out pin connected to a fluid sensor calibration pin (low (0v) initiates calibration while high does not). When I trigger a single digital output to activate a solenoid valve (low to high back to low) the digital output pin holding the calibration pin high spikes down to low then back up to high immediately after the solenoid valve output goes from high to low. I've probed the digital output connected to the calibration pin with an oscilloscope right when the solenoid valve is turned on and off and have noticed a very noisy signal oscillating between negative 5v and positive 15 volts lasting ~ 100us as soon as the solenoid valve is turned off (high back to low). An image of the oscilloscope trace is attached. This behavior is also seen in other digital output pins, briefly activating other solenoid valves.
I am wondering what is causing the creation of this signal in all of the digital output ports when one port is toggled from low to high back to low. Does anyone have any ideas how to remove this behavior?
Thanks in advance!