serial_lte_modem sample: Sending AT commands to modem using putty or TeraTerm does not work.

[pascal_dao]

Hello guys,

I am attempting to send AT commands to an nrf9160 over UART. I started by loading the serial_lte_modem sample and sending commands using the LTE link monitor which works fine. But whenever I try to send the same commands using some other serial terminal  it does not work. I do not get anything back from the nrf9160. I played with the CR LF settings on these serial terminals, and tried manually appending \r\n to the commands, but it still only responds to commands from the link monitor.

Regards.

[Heidi-Irene Harvey Sollie]

Hi!

Are you sure you're connected to the correct COM port? When you connect the DK there should be three OCM ports, but only one of them will let you communicate with the nRF9160.

Additionally, make sure you close the port in LTE Link Monitor before trying to use another program. 

I have not tried using Putty or TeraTerm but I have had success with Termite. You could try downloading it and checking if that works.

Best regards,

Heidi

[pascal_dao]

Hello Heidi,

I am working on Ubuntu 18.04, and I don't think the Termite RS232 terminal is available for Linux. I am using putty, and I opened all 3 /dev/tty ports. When I send an AT command from the Serial Link Monitor, I get the response on the first port, so I think that's the port used by the modem, but then when I type the command directly in the putty terminal on the same port (even with the Serial Link Monitor closed), I don't get anything back. In the picture below the "OK" responses are when the command is sent from the Serial Link Monitor, the "AT" commands are commands typed in the putty terminal with no response. Am I doing something wrong?

Regards,

[Jørgen Holmefjord]

Hi,

I tried this on my Ubuntu 18.04 setup and could not get a response in Putty (or minicom), regardless of what settings I set for CR and LF. A workaround for this issue seems to be to configure the sample with a different termination. I used CR, by adding this line to proj.conf:

CONFIG_CR_TERMINATION=y

You can also try LF or NULL if this does not work for you.

Best regards,
Jørgen

[pascal_dao]

Jørgen, thanks for the tip, I will try that.