VF50 serial UART-A with serial modem connection problem

We are working in a project that will communicate with a serial radio device that uses a null modem cable, and we need to connect to the other side using PPP with PPPOE.

For our communication tests only, we are using a VF50 with Carrier Board Iris to communicate with a serial modem, using the X13 DB9 serial UART-A connector to DB25 modem connector. We connected the X13 DB9 pins to modem DB25 pins like below?

DB9 PIN                Signal Name                DB25 PIN  
     1                     DCD                        8  
     2                     DSR                        6  
     3                     RXD                        3  
     4                     RTS                        4  
     5                     TXD                        2  
     6                     CTS                        5  
     7                     DTR                        20  
     8                      RI                        22  
     9                     GND                        7  

We compile the linux image 2.8 to support PPP and RP-PPPOE.

After installed this new image on VF50, we changed the debug console from UART-A to UART-B using the uboot command “setenv console ttyLP1” to release X13 connector UART-A for our tests.

But after several time and internet research we could not make the VF50 communicates with our modem.

We decided to compile another image to include the wvdial and this package includes the wvdialconf program that is used to check for modems on serial ports.

We used this program wvdialconf in our notebook linux box with this modem connected there too, and this detected our modem connected to this linux box.

But using this wvdialconf program on VF50 the modem is not detected.

We try to connect the VF50 directly to our notebook linux box using PPP across a null modem (direct serial) connection (see: Using PPP across a null modem (direct serial) connection). But it does not works too.

So we are suspecting that we have some problem with the serial UART-A on VF50 with IRIS board.

Any help will be appreciated.

Hi @vbalestero

Could your provide the exact version of the Bsp of your module ( uname -a)?
What changes have you done to local.conf?

Do you have any error log?
Which communication speed are you using?
Did you try using UART-B instead of UART-A?

One thing, you could also try is to disable DMA and check if the communication is working?

Best regards,