You are missing limiting resistors. You'll blow the led's on the optos in the targeted device without them.
So you just need to pass two signals? Apart from the fact that those NAND gates would never have worked with 1 input tied low I think this is OK (assuming DUP3 is the GND for the device and DUP1,2 have pull up resistors) except there's a signal inversion. I think if you sink current to the OK2 LEDs the signal is correct all the way through.
They are NOR gates
When you say to sink current through the OK2 LEDs, are you meaning that I should simply connect the Collector of the triggering device to the Cathode of the OK's that go out to the triggered device?
Maybe, but they are drawn as NAND gates. Anyway as you say you can just use an inverter.
I've made things way over-complicated
Me to as I've been using logic levels rather than just looking at the state of the transistors, ie on of off.So your last circuit will work I think, even without the pull up resistors. As long as the OK1 transistor is driven hard enough to drive a LED.______Rob