Setting CMUX convergence layer

We are using HL6528RD in an embedded device to replace an existing module. The device uses CMUX (and ppp). It looks as if the HL6528RD is set to use convergence layer 2, and is sending the modem status before the payload of eachUIH packet, and expects the host to do the same. This doesn’t work with our existing software. The other modems we have used in the product don’t do this: they just send the payload.

Can you confirm if this is expected behaviour. If so, is it firmware dependent, or is there a setting to allow this to be changed? Is it possible to change the HL6528RD to use the simpler convergence layer 1 mode like the other modems that we use?

Many thanks,

Rod

(hex byte dump below)

I send at+cmee=1 to HL6528 down a mux channel:

-> F9 0B EF 15 61 74 2B 63
<- 6D 65 65 3D 31 0D AB F9

I get from HL6528

-> F9 05 EF 05 0D 74 51 F9
-> F9 05 EF 05 0D 2B 51 F9
-> F9 05 EF 05 0D 63 51 F9
-> F9 05 EF 05 0D 6D 51 F9
-> F9 05 EF 05 0D 65 51 F9
-> F9 05 EF 05 0D 65 51 F9
-> F9 05 EF 05 0D 3D 51 F9
-> F9 05 EF 05 0D 31 51 F9
-> F9 05 EF 05 0D 0D 51 F9
-> F9 09 EF 05 0D 74 D6 F9
-> F9 09 EF 05 0D 2B D6 F9
-> F9 09 EF 05 0D 63 D6 F9
-> F9 09 EF 05 0D 6D D6 F9
-> F9 09 EF 05 0D 65 D6 F9
-> F9 09 EF 05 0D 65 D6 F9
-> F9 09 EF 05 0D 3D D6 F9
-> F9 09 EF 05 0D 31 D6 F9
-> F9 09 EF 05 0D 0D D6 F9

Did you ever resolve this problem?