On Wed, 2011-03-09 at 12:04 -0700, James McKenzie wrote: > On Wed, Mar 9, 2011 at 11:24 AM, aleroot <wineforum-user@xxxxxxxxxx> wrote: > > No, in /dev/ttyS i have only the 4 serial port (rs-232) on the machine ? > > > > Should Linux allocate /dev/ttySX for RS-485 ? What device name under /dev should i have ? > > > It should. It should by the next ttyS device (ttyS4 if my memory serves me.) > Are you using a special board/device for RS-485 communications? Does > this device have a Linux driver? Wine cannot run Windows drivers > because how and where drivers are loaded in the operating system > architecture. > Disclaimer. I've never used RS-485 but some quick research shows the following: - RS-485 is a way of linking a number of devices on a multi-drop cable, so the driver must explicitly switch the transmit side of each node on and off. Devices are referred to as nodes. - RS-485 is a master/slave setup with the master node controlling the other (slave) nodes and controlling which node can transmit. - RS-485 can be full or half duplex. This is a physical choice: half-duplex uses a single twisted pair while full duplex needs two twisted pairs. - RS-485 can be, and often is, implemented with standard UARTs, e.g. an 8250 or 16550. The hardware of some RS-232 serial port adapter cards is switchable to RS-485 with a jumper or you can use RS-485 adapter cards. - Linux *may* set up RS-485 ports as /dev/ttyS[0-9]. What it does would depend on whether the kernel checks whether a serial port is S-232 or RS-485: I don't know what it does. - there is no such thing as an RS-485 transmission protocol. RS-485 only defines the physical link layer. - each node on a multi-drop line has a unique address and any node can send data to any other combination of nodes once the master has given it permission to send. - Linux RS-485 drivers are available. Your distro and/or the people who implemented the communication protocol your app is using should know what adapter cards and drivers are available, so ask them. Martin
