I purchased an MX-990 from Surf Control and a used MSC-400. I purchased the cables, adapters and TRRS jacks to construct my serial cables. The MSC manual says :

Tip: NC
Ring: Transmit
Ring: Receive
Sleeve: GND

I thought I'd read something on this forum about wiring the RX ring to TX serial pin. That's how I've made other serial cables in the past. However my test in CCP isn't working. Should I wire the RX ring to the RX pin on the DB9 adapter? The manual doesn't say much about it. Thanks!!

This is dependent on the device you are controlling.  Some devices require you to reverse (null) the Tx and Rx connections.  That's usually the first thing I try when I'm not getting control over the unit.  Try it both ways.  You won't hurt either piece of equipment if you get it backwards.  There are simple male/female db9 null modem adapters you can get to make this easy.

We usually use the URC supplied cables and cut them open to extend them with Cat5 if we need to make them longer.  I've not tried building my own out of TRRS connectors. 

Thanks for the response! I was doing a little more reading and I saw that you had to upload your codes first before you were able to test. I thought I had done that, but I've been working in so many CCP files, that I decided to start fresh. I created a new CCP file, and tried uploading, and the MSC locked up on me. I powered off, and that was most likely a huge mistake. Now, the STATUS light won't come on, and when I plug a USB into the front, the USB2 light doesn't come on. I'm afraid this thing is bricked. I found the reset button on the bottom, but I can't find the procedure to reset the device. I've tried:

1. While POWER is attached, hitting the button.
2. While POWER is attached, holding reset for 15-30 seconds.
3. With POWER disconnected, holding reset for 15-30 seconds.

No joy on any count. Am I screwed?

If you try to load to the MSC400 with a PC running anything newer than windows XP it won’t work as URC never released a new USB driver

Thank you for your reply! I've been using Win 10 x32 and the driver installed successfully and I did get one successful push. The second push is when the system failed. I don't even get the blue status light or the USB1 light while plugged in. Windows doesn't see the device anymore. Do you happen to know the reset procedure? Thanks!

I'm pretty sure that the reset button on the bottom of the case just needs to be tapped for a factory default.

I read a post on the URC dealer forum where someone was able to revive an msc400 by loading with a laptop that had 32 bit xp on it.

Ok I'll load up XP in a VM and hope that it's seen. Do you know if a tap on the reset needs a special power procedure? Thank you for your help!

As I mentioned, I seem to recall this being a driver issue. Sometimes I resolved weird things like that by changing the USB port on the computer.

I tried a completely separate computer and the in device want even recognized when I plugged it in. I think this thing is bricked.