On Mon, 2008-01-21 at 08:47 -0800, Rob White wrote: > u prolly want the vfd to be master because it has hardware failsafes > builtin, I have the same vfd and i would not loose that front face > plate. Use the modbus under the cover, read teh manual and get back to > me with ur findings please.
You have gotten me to thinking. Modbus can have quite a bit of latency, so I don't know if I would want to rely on it for e-stop class functions. I would think having the VFD alarm relay output in the e-stop chain would be appropriate. That would leave Modbus open for non-real time commands and information. I was thinking of using it for setting speed and direction, but the more I think about it, the latency issue may be a problem here too. At this point, I would have EMC be the master and poll the VFD for performance and trend information, put the alarm output in the e-stop circuit and a DAC and opto-couplers on the normal VFD control inputs (analog speed, forward, reverse). Although, I could change my mind, or I mean, update the spec, at any time. -- 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 [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
