Robustel GoRugged M1000 MP User Guide
RT_UG_M1000 MP_v.2.0.0 Aug. 11, 2017 41/44
Confidential
4.2.3
What should I do if the serial port connection fails?
Check if the serial cable has been connected
Check if the pin assignment of the serial cable has been properly connected
Check if the serial parameters have been correctly configured, and the factory settings of the serial port are
115200, 8, n, 1
Check if there is another program interfering with the communication program, such as a port conflict
4.2.4
What should I do if the modem receives the “No Carrier” message?
If the modem returns a “No Carrier” message upon an attempted call (voice or data), then refer to the table below
for possible causes and solutions.
If the modem returns…
Then ask…
Action…
“No Carrier”
Is the received signal strong
enough?
Use “AT+CSQ” to check RSSI, and see the Signal
Strength Indication table below for more
information.
Is the antenna properly
connected?
Refer to Chapter 2.5.
“No Carrier” (when trying to
issue a voice communication)
Is the semicolon (;) entered
immediately after the phone
number in the AT command?
Ensure that the semicolon (;) is entered
immediately after the phone number in the AT
command, e.g. ATD123456;
“No Carrier” (when trying to
issue a data communication)
Is the SIM card configured as
data/fax calls?
Configure the SIM card as data/fax calls (ask
your network provider if necessary).
Is the selected bearer type
supported by the called party?
Ensure that the selected bearer type is
supported by the called party.
Is the selected bearer type
supported by the network?
Ensure that the selected bearer type is
supported by the network. If no success, try
bearer select type by AT command:
AT+CBST=0,0,3
Signal Strength Indication
Received Signal Strength Indication (RSSI)
Description
0 to 12
Low signal strength
13 to 19
Medium signal strength
20 to 31
High signal strength
99
No signal
