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No PPP connection with Maestro/Lantronix M110 over RS232

reinhu Oct 6, 2020 07:37 AM

I'm setting up a CR300 to get internet connection from a M110 modem on the RS232 port.

The modem is working fine, in the sense that it connects as it should. I can issue AT commands to the modem via serial talkthrough on the logger, and the modem echo is on (ATE1).

But I cannot get a connection working over PPP. We have a similar setup with a M100 which was configured using mobile data assistant. Using MDA is not possible with the M110, but I was hoping there would be some clues there how to solve the problem.

Is there a list with all the AT commands that MDA sends to the M100 during configuration, and the configuration changes it makes on the datalogger itself?


reinhu Oct 6, 2020 03:55 PM

Some more details:

The PPP results in a loopback (with dialstring PPP, same with some other dialstring and I write the expected response (e.g. response ERROR or OK, the connection is already handled by the modem itself).


20:01:49.830  Serial line is looped back.
20:01:49.830  ppp phase changed[1]: phase=11
20:01:49.835  pppos_write[1]: len=25
20:01:49.854  pppos_input[1]: got 33 bytes
20:01:49.856  pppos_write[1]: len=8
20:01:49.874  pppos_input[1]: got 17 bytes
20:01:49.874  ppp phase changed[1]: phase=12
20:01:49.874  Connection terminated.
20:01:49.874  ppp_link_terminated[1]
20:01:49.874  ppp_link_end[1]
20:01:49.875  ppp phase changed[1]: phase=0
20:01:49.875  PPP Loopback detected
20:01:49.875  ppp_link_terminated[1]: finished.


I set the modem with the following AT commands




With the IPTCP command I can connect to the logger remotely over TCP port 6785, but the logger itself cannot connect outbound due to the PPP connection failing. The logger is programmed to send data out (HTTPPost)

Any suggestions?

artyb Feb 9, 2021 06:39 PM

MDA shows the AT commands sent to modems that it works with, which might help you. Alternatively you could make a cable up to watch the serial traffic whilst MDA is running. You can save the logger config before and after MDA runs to see the changes made.

Spyros Jul 12, 2021 09:36 AM

Hi reinhu.

I have the same problem with Lantronix M110 modem.

I tried to setup modem as MDA does for M1003G, but something is going wrong....

Did you find any solution about?

Thanks in advance

reinhu Aug 9, 2021 07:28 AM


I did find a solution (setup M114 with CR300 using PPP on RS232).

I think I was using TeraTerm to do the config of the modem, but any terminal should work.

AT+IPR=9600  (Baudrate set to 9600, match settings in logger (factory default 115200))


AT#IPCELLULAR=1,"your.api.com" (APN setting)

AT#AUTOTCP=0 (this is the key setting for PPP I think, if set to 1 the modem sends the dial string it self, if set to 0 it allows the Campbell logger to control this)

Reading the manual for the modem it seemed like AT#IPCONNECT should be used - this is not the case, use AUTOTCP instead IPCONNECT settings are not retained through reboots. If you dont want to use PPP then AUTOTCP should be set to 1, and possible also need to configure AT#IPTCP

Good luck!

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