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Re: RS-485 port using on ETRAX LX and RS-485-to-RS232 converter by Moxa...




		Hi, johan!

>>>>> "ja" == johan adolfsson <johan.adolfsson@xxxxxxx.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,
>>   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..
 
-- 
		Bor.