Wiring previous-year banner sensors

[Cjmovie]

Originally Posted by Mike Copioli

Please do exactly what Shawn suggested above. We have the same Banner sensor and we wired it the same way Shawn did (except we used the black wire). It doesn't matter what wire (white or black) you use for signal, but only use one. You must, however, get your 12v from the PDP adn a 20 amp breaker or it will not work. You can not get power from the digital sidecar for your banner sensor as it can only deliver 5 volts to the digital IO.

That's how we currently have it wired. The sensor is active as well, showing correct status indications on its LEDs. Also, like I said, if checked with a voltmeter it sends the correct signals. However, if I hook this same line up to a SIG line on the digital sidecar and declare it as an input in code, it does not change in value when the sensor switches. The same code detects switching properly with a microswitch.

We have tried two banner sensors.

[Alan Anderson]

Originally Posted by Cjmovie

When tested with a multimeter, the voltage correctly switches between low and high (for one sensor, 0 and 12V, for the banner, 0 and 3ish). We only get this signal, however, when comparing the signal line to a positive line on the robot - not ground. When comparing to ground, we always receive a 0V signal.

Originally Posted by Cjmovie

...like I said, if checked with a voltmeter it sends the correct signals.

I finally figured out what you're doing with the voltmeter check. The signal line from the sensor doesn't supply a voltage; it is an NPN transistor switching the line to ground. If you put the positive lead of a multimeter on a voltage source and the negative lead on the sensor signal line, you should read that voltage when the signal is active and see an open circuit when the signal is inactive.

I'm a little concerned by the "3ish" you measured, however. I don't see any way for the Banner sensor we're talking about to do that (unless it is broken).

Here's a simple three-step diagnostic procedure that will help close in on the source of the problem. With the sensor disconnected from the DIGITAL I/O SIGNAL pin, measure the voltage on the pin. You should see +5 volts (the pin has a 10k pullup resistor). Connect the Normally Open sensor output wire. You should still see +5 volts. Activate the sensor. You should now see 0 volts. Does this match your results?