PC Control of MTH Engines by Serial Connection to the TIU
To me, MTH makes the best engines and rolling stock for my railroads of choice, the Pittsburgh & Lake Erie Railroad and the Aliquippa & Southern Railroad (where my grandfather worked). MTH has many many engines and dozen of pieces of rolling stock for these railroads. My layout uses only MTH's DCS.
DCS has been out for almost 15 years. I've been waiting for a way to control my layout using my PC. I've always used Windows PC's so this effort was done originally using XP and more recently Windows 7 and Windows 10.
A few years ago, Mike Hewett presented a PC interface to the tethered mode of operation of DCS. He showed how to sniff out the RS-232 packets running between the Remote and the TIU, how to save those packets and how to later transmit those packets to the TIU from the PC.
Mike presented his findings in three videos which he produced around May of 2011. Look at those three videos before you continue with my description.
Look at this OGR Forum thread for a followup:
Mike made more progress as shown in this video from 2013
I think that I first saw what Mike did around October of 2011 as my earliest date stamps on files that I've saved are from that date.
Mike's methodology was to record the packets sent by the Remote when each key on the Remote was pressed. Without regard to the contents of the packets, he saved them in a file. Then, later, his PC program could read up those saved packets and send them to the TIU. He created a very nice touch screen interface and he could run his DCS trains from his PC.
I contacted Mike back then and he sent me copies of his program and I was able to build up his interface to the TIU, sniff out the needed packets and I had a way to control my trains from my PC.
This worked up to a point. When I added a new engine number, I had to run the packet sniffer again and pick up the packets needed for the new engine number. Mike's program only captured a subset of the many, many types of commands that could be sent to the TIU. Mike did not read back responses from the TIU or process any of those returned packets.
I was looking for something more. I needed to understand the protocol over the tether cable.
With a lot of effort, I was able to understand almost all of the communications between the Remote and TIU. I am now able to create packets to control the DCS engines. The packets are complete with correct addressing, command syntax and CRC.
I figured this out by examination of the packets that I could sniff using Mike's original RS-232 interface design and the port settings that he found. Without Mike's insights into the RS-232 data stream, I don't think that would have been able to get a foothold into this protocol.
So again, I figured this out just by looking at the RS-232 stream over the tether cable. No code disassembly, no logic analyzers, no opening up of Remotes or TIU's.
I made up a video (Screen Capture) of the operation of my RTC or Remote Train Control program. This video demonstrates part of its use: