Wednesday, 14 June 2017

Programming the Motorola SM50 under Linux

The Motorola SM50 and SM120 are quite a common radio and pop up on eBay all the time for modest prices. As with all Moto gear they come in a variety of models; wideband, narrowband, 2 channel, 16 channel, 40 watt, 4 watt etc etc etc. There are various model decoders available around Al Gore's Interweb Tubes so we won't be covering that here.

I am the proud owner of quite a pile of SM120 M44DGC20C2AA (40W UHF high wideband) models which are ideal for a repeater blabber box, GMRS or FirstResponder use such as your local Ambulance Squad.

Programming them back in the early 90's (yep, they are even older than that!) was by way of a DOS program running on a lowly i286 PC. But hold on, we are on Linux. How's that gonna work? Take a quick look at this youtube video ...

Things you'll need:

A Linux box (DUH!)
DosBox emulator software (apt-get install dosbox)
SM50 programming software (can't help you there but it's not hard to find)
Motorola GM300 style programming cable or "RIB" (I use a USB one from ebay)

How to do it:

Using your favourite terminal program (I use Yakuake) fire up the dosbox emulator by typing 'dosbox'. If you have a Z: prompt then that part works.

Unpack your SM50 software into a folder. Navigate to that folder and then fire up your favourite text editor. we'll be making a config file called 'sm50dosbox.conf'. Mine looks like this ...

serial1=directserial realport:ttyUSB0
# Lines in this section will be run at startup.
# You can put your MOUNT lines here.
mount C /home/g7ltt/raid/Filestore/DOS
mount M /home/g7ltt/raid/Filestore/motocd/SM50/R030000
Adjust the 'serial' lines to match your USB port. Also adjust the 'mount' lines to reflect your path. In my case 'C' becomes C: and holds a few DOS utilities. The 'M' becomes M: which contains my SM50 software. 

Save your file and the type 'dosbox -conf sm50dosbox.conf' and watch it all fire up. You'll have to configure the dos software to use COM1 but otherwise you'll be programming in no time.

In theory this should work for other Motorola DOS based programming tools for other radio's. However, I've not been able to get the GM300 or Maxtrac software to communicate with the radio. It seems that (for USB cables at least) the serial speed of 930bps is not supported by either the OS or the emulator.

If you get one of the other DOS programs to work please do drop me a line.