Quick question for those that know a bit more about this than I do.
If I have a device which has several programmable open collector outputs, is there any issue with commoning these up to get the functional equivalent of an "OR" gate?
The device in question is an alarm panel which supports activating open collector outputs on certain events, but only supports a single event per output. My plan is to simply tie two (or more) outputs together so that either event can trigger the connected device.
I believe this would work - but would there be any consequences to having the collector of the non-activated open collectors tied to ground through the open collector that is active?
If this isn't a good idea I can achieve the same functionality by wiring each open collector to its own relay, however it would be advantageous to avoid this if I can.
Thanks in advance.
UPDATE: It seems it's definitely possible, as per this quote from
https://en.wikipedia.org/wiki/Open_collector:
By tying the output of several open collectors together, the common line becomes a "wired AND" (positive-true logic) or "wired OR" (negative-true logic) gate. A "wired AND" behaves like the boolean AND of the two (or more) gates in that it will be logic 1 whenever (all) are in the high impedance state, and 0 otherwise. A "wired OR" behaves like the Boolean OR for negative-true logic, where the output is LOW if any of its inputs are low.
That being the case, are there any practical limitations to this? As in, do I need any extra components or anything I need to watch out for?
The other potential issue is, I don't know much at all about how they've implemented the open collector outputs on the device, so that could complicate it as well.