Like you say at that price I can't afford not to try it. If it don't work no biggie.
On 12/26/2015 5:14 PM, Gene Heskett wrote: > On Saturday 26 December 2015 14:09:51 John Thornton wrote: > >> I found this on amazon >> >> http://www.amazon.com/UT-211-Port-powered-Mini-size-PhotoElectric-Isol >> ator/dp/B00GI9GS58/ref=sr_1_3?ie=UTF8&qid=1451156759&sr=8-3&keywords=se >> rial+isolator >> >> Not sure how I might isolate the VFD from the chassis at this moment. >> Well I could machine some delrin standoffs... I have a machine shop. >> >> I will need the control transformer to get power for the monitor or >> just plug the monitor into the wall outlet and power the PC with 240v? >> >> JT >> > At that price, John I'd put one of those in just for the PC's own > protection, and it might well break a ground loop at the same time. > > But verify the speed as I haven't a clue how fast the modbus runs. > Opto's tend to have a speed limit, often below 500 kilobaud. > >> On 12/26/2015 12:51 PM, Bertho Stultiens wrote: >>> On 12/26/2015 07:36 PM, John Thornton wrote: >>>> You misunderstand, all those components are internally grounded I >>>> did not ground any of them. I just showed that the shell on each >>>> component is bonded to the ground connection on each device. >>> Ok, now the real question is whether you can see the difference wrt. >>> to my drawing. >>> >>> The trick is that there should never ever be two or more paths for >>> the current to flow, even if it is just an earth connection (or GND >>> for that matter). >>> >>> The isolation barrier I drew is the low-to-high-power separation. It >>> should be kept physically separated everywhere until you join the >>> power and earth connections at the power supply input. >>> >>> The real problem I see is the connection of the VFD controller to >>> the computer's serial port. Apparently, the computer and the VFD >>> controller both have the GND connected internally to earth. >>> >>> I am pretty sure that the computer's GND is connected to the earth >>> (chassis) of the computer (most PCs have). >>> >>> The VFD controller probably has the same connection, where the >>> modbus serial port's GND is connected to the VFD controller's earth >>> (chassis). >>> >>> If so, then you need to break that loop by electrically isolating >>> the serial port. >> ---------------------------------------------------------------------- >> -------- _______________________________________________ >> Emc-users mailing list >> Emc-users@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/emc-users > > Cheers, Gene Heskett ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
