Help making the Fastrack be an M1206


I’m using a Fastrack as a basic GSM interface to allow my microcontroller to have telemetry. This is based on a previously successful design using the M1206. In the last design I was able to configure the M1206 to use a basic serial port connection at 19200, 8N1, no flow control. I haven’t been able to get the Fastrack to do the same thing yet.

Right now I can connect to the Fastrack using a serial cable and Teraterm Pro V3. I can trade sms messages with my cell phone so all that works fine. The issue is trying to connect it to my microcontroller board through a MAX232 ic to translate it to TTL signal levels. I would prefer to not need any control lines and only use the TX, RX, and ground wires as that’s what has worked in the past. I can only get the Fastrack to talk when the complete set of control lines is connected.

I have used the commands to turn off the CTS and RTS signals, set it to ignore the DTR, and turned on the DCD and DSR lines to always on. I’ve confirmed my 3 wire custom cable is the same as the one that works so there shouldn’t be any wiring error on the TX, RX, and ground wires.

The current configuration report is:
Q:0 V:1 S0:000 S2:043 S3:013 S4:010 S5:008
+CR:0 +CRC:0 +CMEE:1 +CBST:0,0,1
+SPEAKER:1 +ECHO:0,127 &C:0 &D:0 %C:0
+IPR:19200 +ICF:3,4 +IFC:0,0

I’m confident that I’m probably missing some configuration detail that is stopping this from working how I want it to. Can anyone make any suggestion on either looping back a signal or checking some other configuration command to help me get this to work as planned? If I need to add some lines I’ll do it, but I’m surprised that it isn’t working as easily as the M1206 did.



Why would you want to do this?

Why not just use the Integra?

Or see: viewtopic.php?f=53&t=3081&p=11377&hilit=loopback+rts+cts#p11377


If you want the background on the project I quoted it to a prospective client without knowing the local supplier was now selling Fastracks and not M1206’s any longer. Now that I have 2 Fastracks I need to get them working so I can finish the project.

I know the Fastrack is overkill on capability but that’s what I have and it should work. All I need is a basic GSM interface.

So, can you help me figure out what I’m missing here? If CTS and RTS are turned off I don’t know what else needs to be looped back to make it work.