You need to connect device/modem to PC and access it with any COM terminal.
If you are not familiar with using COM terminal, download some graphical tool like: CuteCom or minicom.
Usually these settings work fine:
Device: /dev/ttyUSB0 Connection: 115200 @ 8-N-1 Line end: CR
Here is Example for Huawei E392 LTE/3G dongle.
Send: AT OK Send: AT^SETPORT=? Recieve: 1:MODEM Recieve: 2:PCUI Recieve: 3:DIAG Recieve: 4:PCSC Recieve: 5:GPS Recieve: 6:GPS CONTROL Recieve: 7:NDIS Recieve: A:BLUE TOOTH Recieve: B:FINGER PRINT Recieve: D:MMS Recieve: E:PC VOICE Recieve: A1:CDROM Recieve: A2:SD Recieve: OK Send: AT^SETPORT? Recieve: A1,A2;1,2,3,A1,A2 Recieve: OK Send: AT^SETPORT="A1;2,7,A2" Recieve: OK Send: AT^SETPORT? Recieve: A1;2,7,A2 Recieve: OK
AT^SETPORT=? - Lists the Available interfaces and their numbers
AT^SETPORT? - Show current configuration
AT^SETPORT="A1;2,7" - Sets configuration.
Modem configuration is splitted into 2 parts: before ";" and after.
Once modem is plugged-In - it declares itself in first configuration (normally with at least: A1 - virtual CD drive with Drivers and application). If the drivers are installed - they see the modem and issue a special command to switch to "working" configuration - this is 2,7 interfaces in this example.
Never turn Off PC interface (2:PCUI in this example)!!! Otherwise you'd not have ability to access modem with terminal and change the config.
You can add more interfaces to be active i.e. SD card:
If you get ERROR, maybe the numerical mode is not sorted (16,2,7)→(2,7,16). If your device answers to set command with OK but AT^SETPORT? doesn't show your desired settings, you can try using space in between numerical modes(2,7) and alphabetical modes(A2) like this:
AT^SETPORT="A1,A2;2,7, A2" or with multiple modes: AT^SETPORT="A1,A2;2,7, A1,A2"