[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: RS-485 port using on ETRAX LX and RS-485-to-RS232 converter by Moxa...
----- Original Message -----
From: "Vladimir Bormotov" <firstname.lastname@example.org>
Sent: den 9 december 2002 12:19
Subject: Re: RS-485 port using on ETRAX LX and RS-485-to-RS232 converter by
> Hi, johan!
> >>>>> "ja" == johan adolfsson <email@example.com> writes:
> >> We have some troubles with connection rs-232 device via Moxa A52
> >> 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,
> >> parity..
> >> can anyone comment this? any solutions?
> ja> Hi, I assume you are using 2-wire RS-485.
> 4-wire rs-422.
> 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..
Hmm... if you use 4-wire I can't think of any reason why it shouldn't
work unless you do something with the RTS signal.
I don't have any experiance with the Moxa A52, but perhaps you need to
hardwire the RTS and CTS signals on the A52?
Or could there be a wiring problem or the need for biasing on the