CONNECT string not displayed in CMUX mode

Hi all,

I am using CMUX mode to use the Data and AT in separate DLC port.

Initialization of CMUX was done and working good.

But When I issue Dial Command, CONNECT response not coming and LCP response is coming.

Whether CONNECT string is not consider as Data format or Module itself not sending the CONNECT string.

Kindly help me to sort it out.


Which module are you using?
Are you using any tool or cmux command?


Hi Alex,

We are using HL6528G2.8 Module. I am using CMUX mode only, DLC2 - Data and DLC1 for AT command.

Now I am getting CONNECT response from Modem but I just added some delay after issuing the ATD command.

Previously I had included 2 Sec delay but now I included 3 Sec delay.

While working in normal mode (Without CMUX mode) that 2 Sec is working well. Whether delay plays a vital role in CMUX mode?

Also I have faced another problem, While Data is connected in DLC2 port, DLC1 port AT commands are getting time out every time. But I added print statement in between, It is working fine. Only print statement is different in both the coding.

Whether we need to include delay in querying the DLC1 and DLC2 port or no simultaneous operation should be performed in CMUX mode.?


I have seen these kinds of issues in SL module… what’s your firmware version? also are you running some script?