Hi Anders. For I/O control Modbus TCP/IP is quite a good solution . For motor control (closed loop system) it is not the right one. As you can imagine the matter is the protocol itself . Modbus TCP/IP it's not deterministic so the jitter can be unpredictable and maybe few and more milliseconds in the best case . I know that someone used EtherCAT protocol that is a deterministic one with LinuxCNC but I don't know if for I/O control or motion control . I suggest to you to search for with Google something like "Ethercat LinuxCNC Linux" .
Alex On Fri, Aug 30, 2013 at 4:36 PM, Anders Wallin <anders.e.e.wal...@gmail.com>wrote: > Hi all, > > I'm thinking about various control & data-acquisition systems I want to > build, with different requirements on speed & performance. > > What's the status of Modbus TCP with linuxcnc right now? I found at least > this wiki page: > http://wiki.linuxcnc.org/cgi-bin/wiki.pl?ModbusToHal > > What I imagine doing is something along these lines: > - Have a controller computer with ethernet (particular NIC card is > critical?), using linuxcnc/hal for my control and datalogging > - wire all devices to a dedicated ethernet switch (particular make/model > critical?) > - use ready made Modbus TCP devices for analog and digital IO, I found > interesting ones here http://www.audon.co.uk/edam9000.html but I imagine > there are many more > - make my own Modbus TCP RTU (remote terminal unit) using e.g. Arduino > Ethernet > http://arduino.cc/en/Main/ArduinoBoardEthernet > > Any experience with the latency/jitter for this approach? For some slow > applications like temperature control/logging 1ms jitter will make no > difference, but for e.g. motor control it might be critical. > > thanks, > Anders > > ------------------------------------------------------------------------------ > Learn the latest--Visual Studio 2012, SharePoint 2013, SQL 2012, more! > Discover the easy way to master current and previous Microsoft technologies > and advance your career. Get an incredible 1,500+ hours of step-by-step > tutorial videos with LearnDevNow. Subscribe today and save! > http://pubads.g.doubleclick.net/gampad/clk?id=58040911&iu=/4140/ostg.clktrk > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > ------------------------------------------------------------------------------ Learn the latest--Visual Studio 2012, SharePoint 2013, SQL 2012, more! Discover the easy way to master current and previous Microsoft technologies and advance your career. Get an incredible 1,500+ hours of step-by-step tutorial videos with LearnDevNow. Subscribe today and save! http://pubads.g.doubleclick.net/gampad/clk?id=58040911&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
