Some VFDs are huge electrical noise (EMI) generators. I had an issue a few years ago with an Automation Direct VFD that caused a lot of grief because of electrical noise that being pumped back into the AC line. You may want to consider putting a line filter in the AC line feeding the VFD. Automation Direct sells them. I bought one recently to solve a servo drive noise issue. $72 Some Teco servo drives were pumping noise back into the AC lines. I installed the filter and the problem vanished.
Mount the filter as close to the drive AC input terminals as possible and properly ground it. Dave On 12/18/2014 11:28 AM, Marius Liebenberg wrote: > This in not unique to your setup but rather a USB problem. The thing to > do is to use a isolated USB connection. The problem is mostly due to > ground potential differences between devices. > > I have a circuit if you are interested. > > On 2014-12-18 14:26, Les Newell wrote: >> Yes, that should work. I run my control panel through a usb->rs232 >> converter. I have found the USB side to be a little sensitive to noise. >> Very occasionally it will lose connection. At that point I need to >> restart LCNC to reconnect which is a PITA. This is probably very >> specific to my setup. >> >> By the way if you get a USB->RS485 converter, try to get one based on a >> FTDI chip. FTDI are the most stable and reliable USB->serial converters >> I have found. >> >> Les >> >> On 18/12/2014 11:53, 77dab wrote: >>> Hi all, >>> I have on my hand some mitsubishi VFD with 550w winches. >>> I would like to try to move them using LinuxCNC. >>> the thing is not meant to be Real time, and I've read the modbus module >>> lives in User space and it's not RT. >>> So, my question: >>> Since it isn't RT, can I drive the rs485 thru a USB->rs485 converter, >>> using a laptop? >>> >>> Thanks, Davide. >>> >> ------------------------------------------------------------------------------ >> Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server >> from Actuate! Instantly Supercharge Your Business Reports and Dashboards >> with Interactivity, Sharing, Native Excel Exports, App Integration & more >> Get technology previously reserved for billion-dollar corporations, FREE >> http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk >> _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users >> --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
