we use Hyperterminal (ok - not the most innovative communication program, but working on all Windows platforms) to set parameters in Fastrack Xtend over USB, so to say as “HMI”. Sometimes some modules send cryptic signs inbetween the desired strings and no echo returns. Echo is useful to control the user-input. Without echo the user experiences a blind flight. And the cryptic signs destroy the programmed “HMI”. There are linefeeds, pagefeeds and other annoying stuff. It seems as if there is a change in baud rate, but the “HMI”-strings sent by our software comes in correct rate of 115200bit/s.
Connecting the affected module with Developer Studio corrects the problem quasi permanently. After such a “correction” even Hyperterminal works as desired. But it is not predictable when the problem occurs once more - but sometimes it does.
Has anyone seen such annoying behaviour? And is there any fix for that problem?
I gave up using Hyperterminal ages ago as I was seeing the same (occasional) random characters in my data streams.
Also, Hyperterminal is no longer installed by default on Win7 platforms.
Instead, I use both TeraTerm and PuTTY.
PuTTY recently started supporting comms direct to serial ports (as well as SSH/Telnet/Raw connections over TCP/IP); and Tera Term Pro has a nifty little scripting language that I use to automate repetitive tasks (i.e. configuration of devices, uploading firmware etc).
Try one (or both) of the above terminal emulators and see if you still have the same issues.
Oh, and I’ve also seen this occasionally where the voltage levels were not sufficient/correct to drive the TTL-RS232 converter. In particular, I was using a 3V3 FTDI cable connected to a Q2698 and was getting back garbage. It turned out that although the PTS stated that the Q2698 was a 3V3 capable UART, the TX lines were only being driven to 2V8(ish) which was not enough to cleanly trigger the 3V3 logic in the FTDI cable. Moving to a 2V8 interface fixed things up.
I would check the AT+WDM command. When you use developer studio it configures the module in development mode(AT+WDM=1). If you use any other terminal program you will see a lot of garbage. This can happen if you use Dev Studio and don’t close the port properly.
If this is the case it is easy to fix. Run the following commands: