On Sun, 2008-02-03 at 18:12 +1100, Peter Homann wrote: > Hi Kirk, > > A couple of things. > > The ModIO I sent you has a RS232-485 converter built in. With this you can > run > a serial cable from the ModIO to the PC, then run additional Modbus devices > from the RS485 terminals on the ModIO. It saves from needing an external > converter. > > When using RS485 I recommend using full duplex rather than 1/2 duplex. Some > times there are issues with buffers in the PC and timing for switching the > transmission direction > > Cheers, > > Peter.
I'm looking forward to getting my hands on it. Since I don't know what I am doing yet, I was thinking that I could try to address the timing issues. Is it that the serial port uses internal buffers, so you don't know exactly when data will be sent and due to the query and response nature of Modbus, the timing is important? I seem to recall that some parallel ports had the same problem, but the driver was broken, which disabled the buffer, so ports with fifo's were okay to use with EMC. I wonder if the buffers on the serial port could be disabled too. It would be nice to be able to use Modbus in its common forms. But since you have covered this territory, you could probably talk some sense into me. -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending) ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
