RS-485 Over A Half Duplex Serial In CentOS 6.5

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Hi, I am trying to make a program in C to communicate with a temperature sensor over my serial port that uses RS-485 and is a half duplex. I am however having trouble getting the device into RS-485 mode, is it possible to use RS-485 mode in CentOS 6.5 or does it only support RS-232 mode?

3 thoughts on - RS-485 Over A Half Duplex Serial In CentOS 6.5

  • the problem is, a 232-485 converter needs to be told when to be in transmit vs recieve mode for a half duplex single pair circuit to function. as that article says, this can be done by using the RS232 RTS
    signal to control the RS485 line driver, but the linux driver has to know about this and support it.

  • Gotcha and yes that was the problem I was having, I could transmit but would just get bounced but what I transmitted due to not being able to set transmit mode. So I basically have to use

    /drivers/serial/crisv10.c: serial driver used on the Cris ETRAX platform
    /drivers/serial/atmel_serial.c: serial driver used on Atmel platforms
    (AVR32 and AT91 included)

    for my drivers. Sorry I am not a fully hardware guy so am a little lost at some of this stuff, but I know the software is not working since the hardware has no way to know how to interact through software.

  • Hi Jason,

    I don’t know what temperature range you want to sense. I have had success using I-Button temperature sensors directly on a USB RS232
    connector. With this set up you can have multiple sensors on one line as each sensor has a unique address.

    The software I used for this was from a book Linux Toys by Christopher Negus and Chuck Wolber. ISBN: 0-7645-2508-5

    Regards

    ChrisG