FXT002 - USB for development, serial for interface

Hi All,

So far I have been developing using the serial port, now it is time to attach the serial port to a PLC to move on to the next stage of development.

I am hoping that I can move over to the FXT002 USB interface for development and debug but I can’t see any options on Developer Studio -> Target Management that will allow me to connect via the USB port.

Having powered up the FXT002 and plugged the USB into an PC running XP, the device manager indicates a “Sierra Wireless Device” under Modems, so I appear to have some USB drivers loaded, but are they correct for development ?

Many thanks,


Under Windows device manager you should be able to see a modem now installed. If not you might need to download the USB driver of the SiWi site. If you can, right click on it and look at Properties, second tab will show you which serial port it is acting as, the Diagnosics tab will allow you to request info - click and you should get a response form the modem. If you can, then just set up Dev Studio to this new COM port, set speed to 115200 and you should be talking to it!

Thanks, turned out to be attached to COM7. It took some fiddling and a reboot before I could enter COM7, and then DS crashed, but so far so good.

From the modems view of the world, what are the device names for it’s serial and USB ports (presumably it does have two different device names ?)

Many thanks,


It does - see the ADL User Guide.

Ahaah, RFTM - fair comment.

I have had two instances of a terminal running, one attached to COM1 (serial) the other to com7 (USB). Both are able to talk to the modem and I can’t see in difference between them in terms of behaviour or replies to AT commands. So far so good.

I can reliably download a simple hello world app using Developer Studio over COM1, but when I change ports and attempt to load firmware via COM7 (the USB port) DS repeatedly reports download failure.

When attached via COM7/USB, DS is able to fetch modem status via the ‘refresh target info tree’ button, so it does appear to be connected.

Any thoughts about how to fix this apparently unreliable USB connection ?



I am using DS Build Version

Full USB connection is more complex than a simple UART one (or even USB-RS232 converter), since each time the target reset, USB stack resets too and Windows COM port falls down, needing to explicitely close and reopen the connection.
As when you require a download, it leads to a target reset, you fall exactly in this issue.
We are investigating on finding a smart solution to handle this transparently in Developer Studio 1.2.0

I never download via the USB port, you weren’t able to in the past, so I guess not many people do this.

For a long time, the Wavecom devices would only download via UART1;
ie, AT+WDWL would not work on any port other than UART1.

It is a fairly recent update (R7.3 or so?) thAt AT+WDWL now works on other UARTs - including USB.

It is possible to do, but you need to be very careful about the way that the PC sees the port “disappear” when the unit restarts; this can really mess-up some comms software - again, to the point that the only recovery is to restart the PC.