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IO Port Output as 12V Trigger
sonny
Junior Member
in AMX Hardware
Anyone ever used an IO Output as a 12V trigger, I've used these for inputs a number of times, but I'm out of relays on the processor and need a couple of outputs. If I read correctly, the pins are shorted to ground when the channel is turned on in the processor. When I turn on I can measure 12V between the output and the 12V connection, but when off I get 8V. I'm guessing this is due to it being a solid state output. The problem is when I plug into the Amp, the channel gets turned on, apparently reading this as an input??
Do I have to backend with a relay to make this work?
Thanks, Sonny
Do I have to backend with a relay to make this work?
Thanks, Sonny
Comments
E
http://www.altronix.com/index.php?pid=2&model_num=RB610
Run 12v to the + side of the coil, and a wire from the IO output to the - side of the coil. You will then still have to hook up the NO/C/NC sides of the relay like you normally would.
This keeps the IO's isolated and the power level safe.
Kevin D.
A word of warning.
I'm not sure what protection circuitry is inherent to the NetLinx IO ports, but if you plan on driving a relay coil directly from an open collector IO port such as on a NetLinx you should definitely have a reverse biased suppression diode across the relay coil. This removes the potential for voltage spikes generated when the coil magnetic field collapses when de-energised destroying the IO port.
A quick Google search turned up : http://www.autoshop101.com/forms/hweb2.pdf. Page 12 explains why this is the case.
Most pre-manufactured relay boards have a suppression diode or other protection circuitry built in and this may be true of the Altronix product linked to (the photo wasn't clear enough to tell). If you're not planning on using such a board - 5c part to save a $1000 unit? Priceless.
Here's some dope on the IO and the relay.
http://www.amxforums.com/showthread.php?1258-What-are-IO-ports-for&highlight=protection+diode