Cannot share Telit SSL session between Python code and AT serial interface

[Sol Boucher]

This may be a better question to pose to Telit directly, but I’m trying it here first since your response time is so good. Again on the MultiConnect OCG-E with MTSMC-H5-U, I can bring up an SSL socket like so:


def waitforready():
tmp = ''
while not len(tmp):
tmp = MDM.read()

MDM.send('AT#SGACT=1,1\r', TIMEOUT)
waitforready()
MDM.send('AT#SSLD=1,443,"our.server.hostname",0,1,1000\r', TIMEOUT)
waitforready()


I can do AT#SSLSEND=1s from the Python code and successfully send data to the server. However, when I try to run that same command from minicom via /dev/ttyACM0 with CMEE set to 2, I get: +CME ERROR: Resource used by other instance.
Is there any way to write to the same SSL connection from both Python and the serial interface, or to transfer use of the connection from Python to the serial interface once it has been brought up?

[Lonny Knudson]

Hi Sol,
With the current radio firmware the answer is no. May I ask why you are using the Telit IP stack rather than the Linux stack to open the SSL connection?

[Sol Boucher]

We were hoping to use a Python script to have the chip bring up the network connection and SSL connection automatically when it receives power, then use the pre-established SSL connection via the serial interface once our UI flow has completed.

[Lonny Knudson]

Hi Sol,
Have you considered establishing the network link using pppd and using python on the OCG to manage the SSL link ?

[Author]

Posts