Suspend PPP connection with modem


I am using an RCM6700 module to establish a GRPS connection with a Modem (SIM900) using DynamicC PPP library.

I need to be able to check the signal quality on the modem via AT commands, but without disconnecting the GPRS connection.

Is there any way to go from data mode to command mode without hanging up the connection and then returning to data mode?

I appreciate your help.


Hi, I Think +++ command is helpful.

Check the page number 26 at the below link about the command details.

Hello and thank you for your answer.

Perhaps I wasn’t completely clear in my question.
In order to send a +++ command, I need to send it manually through the serial port, but I don’t want to mess with the PPP library which might be using the port for something else at that same time.
I’m not completely sure that using the RS232.lib and the PPP.lib libraries on the same port at the same time is safe.

So my question is: how can I go to command mode using the PPP library to make sure everything runs smoothly?

Thank you. I appreciate your help.

Do you find any solution to your problem?

I’m facing the same issue.

Thank you

Hello, It seems to me that , there are no direct Dynamic C APIs to check the GPRS signal strength.

You are correct. There is no DynamicC API funcition to check GPRS signal, but it is not hard to implement.

Some time ago you proposed to use the +++ command. I agree, and It is also possible to use the DTR pin for the same purpouse.
My concern is that I have no way of telling DynamicC PPP library that I am going to “get in the middle” of the communication to use the serial port for myself. How can I be sure that I won’t crash the PPP library or that the library will send rubish on the serial port while I am trying to get in the middle?

Hello, It seems like without going to be command mode, you can not use the At commands to get signal strength. Check the below doc