I've used an RS-232 to 485 converter with the BBB, and it works acceptably for my needs. The major problem I have is that Linux and the OMAP serial drivers are hopelessly slow. Input is interrupt-driven, so I'm not losing any input. But if I try to output packets with timing limits needed by Modbus, it can't be done. It's not the hardware--the device I'm talking to on the other end is a cheap AVR running at 8MHz, and it can handle it just fine, because it doesn't have a huge OS in the way.
Since I was in control of both ends, I solved the issue by abandoning Modbus protocol and made my own more timing-tolerant one. How to solve your particular problem would depend on your needs. On Sunday, December 28, 2014 6:40:34 AM UTC-8, faimbs wrote: > > Hello! > > I communicate with Modbus RTU over Uart4. > I use a RS232/RS485 Converter. > > At the PC no Problem, but on the BBB I receive not the complete answer. > I receive only 120 to 123 bytes. But it shouldbe 157 bytes. > It seems I lost some bytes from the end of the answer. > > In the Linux PC it works without problems. > > I set the serial to raw. > > Has someone tried similar steps? > > Thanks -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
