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IO light stuck ON
JOHNBONZ
Posts: 99
On my NI-3100, there are 8- IO ports, with amber led. My first light, channel 1, is stuck in an ON state . Does anyone know of a way to reset the led's to off?
I set up a screen to toggle the lights ON/OFF and all that works fine as the LED's toggle ON/OFF
But I ran into issue when I set up a doorbell push button ---one wire to ground and the other connected to channel 1 on device 17 on back of controller.
Then I connected 12 volt to other end of the door bell push button, and the other to the +12 volt on the port 17 of the IO in back of controller
So when I press door bell button the led lit up,then when I released door bell button, it turned off -- but after playing around the led on channel one stayed lit.
After I removed all the wiring to the IO port in back of the controller and rebooted, the led for channel 1 stayed lit.
so:
on door bell push button
- screw 1 - I have black and green wire
- screw 2 - I have red wire feeding 12 volt
on IO port in back of controller 17
- Gnd - black wire
- channel 1 - green wire
+12 volt - red wire
So is there a command , a setting to reset the LED's on the IO port to be reset to OFF?
I set up a screen to toggle the lights ON/OFF and all that works fine as the LED's toggle ON/OFF
But I ran into issue when I set up a doorbell push button ---one wire to ground and the other connected to channel 1 on device 17 on back of controller.
Then I connected 12 volt to other end of the door bell push button, and the other to the +12 volt on the port 17 of the IO in back of controller
So when I press door bell button the led lit up,then when I released door bell button, it turned off -- but after playing around the led on channel one stayed lit.
After I removed all the wiring to the IO port in back of the controller and rebooted, the led for channel 1 stayed lit.
so:
on door bell push button
- screw 1 - I have black and green wire
- screw 2 - I have red wire feeding 12 volt
on IO port in back of controller 17
- Gnd - black wire
- channel 1 - green wire
+12 volt - red wire
So is there a command , a setting to reset the LED's on the IO port to be reset to OFF?
0
Comments
I do not understand exactly what you did by reading your post, but if somewhere in the setup you connected 12V (through the doorbell button) to that I/O input while it was pulled low, there is a real possibility that it is now broken. In that case the transistor where you applied 12V to it's collector is now effectively a short circuit because there ran too much current through it and the LED is actually tellling you the correct state.
Happened to me once when a colleague accidentally connected a diode accross an external relay with the wrong polarity. The maximum current of the power supply ran through the I/O pin and it was forever short circuited....
Richard
Note: This IO port uses 5V logic but can handle up to 12V without harm. It
can handle up to 12V on the input. At higher voltages you run a higher risk of
surge damage.
I used a 12 volt power supply when I hooked up door bell button to channel 1 of IO port
But why not find out? connect a resistor (10K) from the 12V on the controller to the IO pin and measure the voltage on the pin with a multimeter. It should be a few 100mV when the channel is on and around 10V or so when it is off.
More info from the manuals:
-That last item about the input impedence means that if you hit it with 12v directly, there is at least a 22k resistance in line already, so the current should be limited.
so there is a 5 volts to each channel, except the one I shorted apparently - or since it is in ON state I get a lower voltage reading. so I wonder if I can get that channel to shut off and maybe return to 5 volts
Correct, no voltage is needed, but it seems that's what the OP did. If you want to control a relay, a light bulb or a LED (with a series resistor), you would connect one end to, say, 12V and the other end to the port. That's completely valid.
No, I don't think that's what it means.If there was a 22K resistor in series with the channel when it is 'ON', you could get about 500uA (0.5mA) before the voltage on the channel would reach 12V and it would be impossible to switch something like a relay. Although not exactly clear, it probably is the input impedance (that's AC 'resistance') when the channel is off, that is when it is used for voltage input. The OP seems to have used it as an output AND applied 12V to it. That can go wrong...
@JOHNBONZ: If you shorted it (and it looks like it) most likely you can't get it to shut off any more. The transistor that 'acts like a switch to ground' is likely shorted and you either live with that (there are 7 other channels...) or send it in for repair.
From:
https://en.wikipedia.org/wiki/Electrical_impedance
My guess is that the 22k impedance is when the IO is being used as a passive input. There would have to be an impedance difference between the Off and On state when being used as an output.
When the port is used as an output, it acts like a current sink. It is most likely configured as an open collector (or drain) with some sort of weak pull-up to 5 volt. So when used as an output, when actvated, the port effectively shorts the pin to ground. I don't know if it's internally current limited, but would not be surprised if it isn't, that's more difficult than it seems, especially if you want to sink a substantial amount of current (which 200mA is, in this context).
So my best guess, without knowing anything specific of the electrical internals of the I/O ports, is that the OP connected the power supply to the pin when it was 'on' (pulled low) and destroyed the internal current sink (transistor). So the stuck LED is actually correct, the output is low and wil stay that way, short of repairs.