Not yet. Will definitely get back with results. Thanks.

Did you get a chance to test wiring? 

Arturo. I'll definitely gave that a try. Thanks.

Considering what you are saying, it is very clear that the output in question is +5vdc Open Collector.   That means that when it is active, it sends a GND signal and when it is inactive, the signal remains floating.  It is OK to wire it like you are doing with the resistor, but you can also wire it without a resistor if you connect the +5vdc into the COM terminal for the bank of inputs you are using, and you feed the output of the driver into the input terminal you are using.  This way when active the ground of the output with close the circuit with the +5vdc on COM.

It would be great if you could give it a try and feedback on how it goes.

Thanks Aturo. I was operating from that assumption with the C94 Port 2 COM to the Anaheim COM and each C94 Port2 input to the Anaheim TTL outputs. (I can't seem to upload a snapshot of my wiring diagram.) The limit returns from the Anaheim aren't contact closure or I would do as you suggest.

I measured the Annaheim outputs - LOW = 0.2v, HIGH = 2.47v. It seems the 0.2v was "tickling" the C94 inputs enough to flicker and trigger them.

I solved this by adding a 330ohm pull-up from each C94 input to the 5v supply. That makes them HIGH when the Anaheim is LOW (floating) then, when the Annaheim goes HIGH with 2.47v, the C94 goes LOW. Kinda backwards but it works. I switched UCCNC inputs to trigger on LOW and all the limits now work.

Cheers,

Michael

I think there is confusion on how inputs on the C94 work and your issue may be related also to not using the correct common for the inputs.  It would be great if you could add pics of the wiring.

Note that the C94 has bidirectional optos that that +5vdc to +24vdc signals.  So you really just need to make sure you wire into the COM terminal for the bank of inputs the correct signal.  So the inputs do not really need pull-up/down resistors.  We made it this way to make it simpler to wire.  I know it is very common to use the pull-uo/downs on non-isolated breakout boards, and we use them in boards like the C11G, but we feel we are doing it in the C94 is easier and very flexible.

From what you are saying it appears you are using +5vdc TTL signals for limit switches.  Since for this you probably do not need isolation, you can use the +5vdc SOURCE that is on the board.  You can run a jumper cable from GND to COM of the input bank that you are using and +5vdc to the switch and then into the input signal.

I think this wiring sample will work for you:

https://www.cnc4pc.com/blog/post/wiring-c94-with-switch-mechanical-limit

Thanks for the reply Arturo. To clarify:

My outputs to the machine are working great. Pulse and Direction outputs are working perfectly.

My problem is the C94 inputs are floating above 0volts, causing their state to flicker. I am using Port 2 Inputs 10,11,12,13,15 for detecting the limit state of my machine. The Anaheim driver is sending limit signals to the C94 as 0-5volt TTL signals.

It is common to add a pull-down resister to chip inputs, like those on the UC300ETH, in order to keep them from floating and false triggering. The value of that resistor depends on the impedance of the C94 input.

Since this is a question about the UC300ETH, I'll ask about pull-down resistors on the CNCDrive forum.

Thanks!

For the other readers of this thread:
Here is a quick review of how to calculate pull-down/-up resistor values.
https://www.youtube.com/watch?v=4BK00lErS8I

And, here is a very detailed article on the use of pull-down and pull-up resisitors with computer logic:
https://www.electronics-tutorials.ws/logic/pull-up-resistor.html

It appears you need to use a different common for the step and direction.  Note that next to the step and dir terminals there are also +5vdc and ground terminals. Change the common and let me know if that fixes the issue.

My c94 is successfully driving the motors via the attached Anaheim Automation driver. The returns from the high/low limit switches are acting weird, however. The Anaheim sends ttl signals back over parallel cables, the pins of which I've wired to port 2 inputs. When high, the inputs are solid but when low, they flicker. 

Should I add a pull-down resister to the inputs? If so, what value?

thanks,

Michael