Serial communication problem


I have problem while im using serial ports to communicate with other device.
Im communicate with it using modbus communication but sometimes some data is missing (few bytes less, sometimes few bytes more). Every byte counts, so its important to get whole modbus frame.

Im tried to use different uarts, but nothing changed. I tried to set lower baudrate and on lowest values this was working good, but i cannot communicate with some devices with 1200 or 2400 baudrate!
Anyone had similiar problem?
Maybe someone have any ideas what can cause this problems?


Which board is this?


pyromanpl, we need more details. Which module are you using for UART opposite the BBB ? Then exactly what are you doing ? details details . . .

Hi guys,
thanks for responses.

Im developing soft in java, its simple and work already on many different system and architectures.
This is simple: my program send query frame to custom device and device sends reply with some data as modbus frame.
And here is problem. When i have baudrate > 2400 then some troubles seems to appear. I know how many data should i get, for example i know that frame will be 100 bytes but i receive 97bytes.

I tried to use UART1 and UART2. Same problem on both.
Im using BBB, OS angstrom, kernel 3.8.13.

I have the same problem, but only when using multiple serial ports at higher baudrates. I use libmodbus including MODBUS_ERROR_RECOVERY_PROTOCOL.
I notice many CRC errors and timeouts when using four serial ports together.

I am having similar problems with the BBB(Angstrom image). I have installed the recommended serial cape from circuitco. I have gone through many tutorials on getting the the cape addressed properly, but all of the efforts have been to no avail. I am trying to get the BBB to communicate with a Juniper NS5GT through minicom. I have minicom online but it is showing nothing from the NS5GT. I am using a serial DB-9 cable, not a usb to serial converter. I am trying to keep this board as low power as possible. Thanks for the help.

I am facing same problem in serial communication.
I am communicating with other device using UART -4 port on BBB (Debian operating system, with latest release of 2014-05-14).
UART 4 port was enabled from uEnv.txt. Baud rate is set to 57600.
Hardware used is standard one, suggested on BBB webpage. When communicated through PC, other device communicates well and there is no problem in communication. But when BBB is used, communication breaks intermittently. Since code is written in a continuous loop, communication gets re-established after few cycles.
Priority of working software was also changed to highest level, but nothing worked.

Same procedure was followed for different baud rates and on UART -2. But problem still exists.

Can you suggest some ideas to solve this problem?