I used AUX 501 and 502 to create IR devices in the MX-900 editor, imported them into the MSC-400, and converted the devices into a smart macro group. But something's not right, as the macros don't seem to transmit anything. I tried both quick testing from the editor, and also actual remote triggers (since the quick testing is a bit flaky), but no cigar.

I checked that the MSC-400 is recognized as a keyboard device in the computer in which it's plugged. The USB2 light is on. The status light flickers when I try to transmit a keyboard command, either from the editor or from the remote. But it's not doing anything on the PC itself.

What did I forget?

What you are doing is incorrect.

There is no need to import 501 & 502 into the MSC-400 then convert to smart macro - (WILL NOT WORK)

All there is to do is
1. set your MSC-400 and MX-900 to the same ID
2. Open IR databse navigator in MX-900
4. Drag & Drop codes 501 & 502 to buttons on MX-900 from IR Navigator
3. Plug USB in to the rare port on the MSC-400

Thanks a bunch - that did the trick. I guess it's so simple I was overthinking it :-)

Though again, I notice that there is apparently no way to quick test this. Have to drag the codes to the macro, but 'play' won't do it, you have to actually download the config to the remote. Oh well.

Hold that thought.

How do you do keyboard emulation within smart macros???

In the macro, the remote will do what pertains to the keyboard functions while the MSC-400 do everything else.

It is perfectly fine to combine remote functions and MSC-400 functions once they're not doing the same thing

Yes, but you can't trigger keys conditionally then. Something like:

if (my htpc is off) then
send space key (to wake it up)
else
do nothing

I can probably work around that somehow, but I hope URC will update the software so that the keyboard can be a device inside the MSC-400 like any other IR or RS-232 device.