[HL8518] 921600 baudrate and CMUX

IoT Modules Legacy HL Series
1

I’m trying to change the baudrate of the HL8518 to the maximum value in combination with CMUX: 921600 (AT+IPR)

According to the specifications, CMUX supports transmission up to 1Mbit/s (no sure why this is not 921600??)

However after a few seconds the CMUX just explodes and the module start responding in non-cmux packages.

Is 92600 not supported for CMUX? 230400 seems to work fine

2

Hi,

921600 is not supported by +CMUX. See below AT log and AT guide Rev19.0.

ATI
HL8518
OK
ATI3
RHL85xx.5.14.0.7.5.20171229.x6255
OK
AT+CMUX=?
+CMUX: (0),(0),(1-7),(1-1509),(1-255),(0-5),(2-255),
OK
//AT+CMUX=,,<port_speed>,,,,,,
//<port_speed>
1 9 600 bit/s
2 19 200 bit/s
3 38 400 bit/s
4 57 600 bit/s
5 115 200 bit/s
6 230 400 bit/s
7 1 Mbit/s

3

And why does it support 1Mbit/s while this is not a supported baudrate, whats the purpose?

4

Hi roel0,

For +CMUX, the HL8518 respects the 3GPP TS 27.007, and 921600 is not supported. Refer to https://www.3gpp.org/ftp/Specs/archive/27_series/27.007/
(Chapter 5.7 Multiplexing mode +CMUX)