MC7455 PPP CGDATA problem


#1

I try to use MC7455 on old embedded linux system (The MC7304 devices are working well).

ATI
Manufacturer: Sierra Wireless, Incorporated
Model: MC7455
Revision: SWI9X30C_02.30.03.00 r7804 CARMD-EV-FRMWR2 2018/07/25 01:10:04
MEID: 35907206042423
IMEI: 359072060424237
IMEI SV: 17
FSN: LQ646445120310
+GCAP: +CGSM,+DS,+ES

OK
AT+CGATT=0
OK
AT+CGPADDR=1
+CGPADDR: 1,0.0.0.0

OK
AT+CGDCONT=1,“IP”,“met”
OK
AT+CGATT=1
OK
AT+CGACT=1,1
+CME ERROR: unknown
// wait few seconds
AT+CGACT=1,1
OK
AT+CGPADDR=1
+CGPADDR: 1,172.31.123.145

OK
AT+CGDATA=“PPP”,1
ERROR
ATD99**1#
ERROR

I have no any idea to fix that. What is the difference between MC7304 and MC7544 ?
Istvan


#2

@sebist,

You don’t need to do the at+cgdata command also try it with the dial string 99*1# (i.e. atd99***1#).

Regards

Matt


#3

Hi Matt,

Thanks your answer.

Similar result:
AT+CGDCONT=1,“IP”,“met”
OK
AT+CGATT=1
OK
AT+CGACT=1,1
+CME ERROR: unknown
AT+CGACT=1,1
OK
AT+CGPADDR=1
+CGPADDR: 1,172.31.123.145

OK
ATD99**1#
ERROR

Regards,
Istvan


#4

The real command is “ATD*99***1#” of course.


#5

@sebist,

For clarity I have uploaded a file of me doing the same operation at the link below and it works so I am not entirely sure what you are doing that could be different.

MC7455 PPP atd command.txt (318 Bytes)

Regards

Matt


#6

Hi Matt,

Thank you, this is working on my laptop too(Ubuntu 16.04, ModemManager off). I would like to limit the connection speed.
I would like to get ‘CONNECT 100000000’ intead of ‘CONNECT 150000000’ .
Is it possible?
Istvan


#7

@sebist,

The speed is not really 150000000, this is just convention to have a speed after the CONNECT message (some modems do not have a speed) with the high number indicating we are past the days of hayes modems at 9600bps. You are going to effectively be limited to the speed of the weakest part of the link between the host system and the end IP server be it the serial port, resources allocated from the LTE network, processing capability of the host system, back end IP, etc.

Regards

Matt


#8

@mlw,

It could be a limitation of my USB port.

Thanks,
Istvan


#9

@sebist,

If it is USB 2.0 compliant then it should be fine.

Regards

Matt