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Re: RS-485 port using on ETRAX LX and RS-485-to-RS232 converter by Moxa...
>>>>> "ja" == johan adolfsson <email@example.com> writes:
>> We have some troubles with connection rs-232 device via Moxa A52 Smart
>> Converter to devboard's rs485 port. Programm inside DevBoard can't
>> get valid data from rs-232 device, behinde conerter. In other side,
>> Moxa A50 converter work perfect.
>> programm use /dev/ttyS3 device as serial device, set speed, baudrate,
>> can anyone comment this? any solutions?
ja> Hi, I assume you are using 2-wire RS-485.
ja> Are you controlling the RTS signal from the DevBoard program manually
ja> or using the RS-485 ioctl() to configure RS-485 (TIOCSERSETRS485) and
ja> write RS-485 data using the TIOCSERWRRS485 ioctl()?
ja> The RTS signal controls the direction of the RS-485 line so you must
ja> do something with it. You must use kernel 2.4.19 with the patches
ja> from http://developer.axis.com/download/linux/ for RS-485 to work.
no, we don't use any rs-422/485 specific IOCTLs. /dev/ttyS3 used as
simple rs-232 port.
ja> For 2-wire RS-485 it is the RX pins that should be used, they can
ja> switch direction (with RTS), but the TX pins are always transmit.
ok, we try 2-wire connection..