On Thu, 2008-08-28 at 17:43 -0400, Stephen Wille Padnos wrote: > Belli Button wrote: > > >Hi all, > > > >Is it possible for EMC to talk to a PLC with Modbus interface through the > >COM port? > > > > > Hi Greg. > > Yes, it's possible. I have written modbus modules for a PLC and the > Automation Direct GS2 series of VFD. The PLC module was for a specific > program running on a particular PLC, so it's probably not too applicable > here. I haven't checked in the GS2 VFD driver yet, but at the moment I > can't remember why not. It may have been a license issue - I think the > library I used has switched from (L)GPL2 to (L)GPL3, which was some > cause for concern. > > In general, Modbus communication is non-realtime - the module I wrote is > a userspace program that just refreshes the modbus data every N seconds > (settable with a HAL parameter). > > Maybe someone can jog my memory as to why I didn't check it in, and I > can fix the problems so it can serve as a base for others to make > additional modules. > > - Steve
I am interested in what you did. I think that if you use Modbus RTU that the RS-485 interface can be an issue. I seem to recall that flow control and timing had to be considered for each system being connected. Just in case, my Modbus page is here: http://www.wallacecompany.com/machine_shop/EMC2/modbus/ -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC/EMC CNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending Craftsman AA 109 restoration Shizuoka ST-N/EMC CNC) ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
