Question:

Does ANYONE know if the AXB-TC boxes, when running in carrier-off mode (via a \"SEND_COMMAND TC, 'CAROFF'\" command), produce a TTL 5VDC signal? 

A piece of equipment never previously controlled by AMX requires 5V TTL logic and I didn't know what the TC's signal looks like when IR carrier is stripped.  This is for a specific piece of equipment called \"Airshow\" which is a DSS satellite system for installation in aircraft.  The remote they use is a Sony RM-Y800. Perhaps you could look at the RM-Y800 IRL file for any clues to the 5v TTl logic signal?

Oh, by the way, before anyone asks, the way the Airshow is controlled via the Sony RM-Y800 remote is they use another piece of equipment which has an IR window, and you aim the remote at the window and the device changes the IR into 5V TTL where it is connected to the Airshow via a 2-pos terminal strip on the back of the unit.  This device requires 28VDC to work, this job would need 4 of them, and there is very little room for addition of this equipment (this is on a custom airplane and all the electronic equip is already packed like sardines onto this plane).

Answer:

The TC outputs, while not driven directly by transistors, output the equivalent signal levels. It's possible, but not likely, that we don't supply enough current.

The IR output, without carrier, generally sits at 0V, jumps to 5V for the signal. If you looked at it on a scope you'd see something like the following. Note that these signals are square waves - they should look like boxes, not mountain ranges.

When you add the carrier, and stretch out what you see on the scope, the high (5V) parts of this signal look like:

instead of

Now if you switch the TC from IR to SER, all you really do is invert the signal.

I would recommend looking at the signal on the Airshow when their device is controlling it.  Once you know what that signal looks like, you can compare what the AXB-TC is producing.  In fact, if you can use an IRIS to capture at this point, you are virtually guaranteed success.