Then this proves the cause. The isolators provide a low impedance path to ground. It is just current-limiting resistor and a forward-biased diode. With this low impedance to ground there is no way for EMI to cause the voltage on the wire to raise.
On Wed, Oct 13, 2021 at 1:40 PM Peter Hodgson <[email protected]> wrote: > > Well............! > > A quick update for those that are interested. > > The HPCL2631's won the postal race and arrived in the mail today. > > I made up a little 'interface' board to mount them on with the pull ups, > caps, etc. and fitted that board this evenening. > > After an initial check on the index pulse I ran my G76 program (in air) > for the M47 x 3.0 thread, that as giving me so much trouble, whilst > watching Halscope for the encoder index and I didn't see one ghost > pulse. I did see one that was missing over the 7 mins but I don't think > a missing pulse is going to give me as much trouble as ghost pulse and > anyway that could have been a software glitch. > > Too late to cut metal now but I will tomorrow. > > Looking good though! > > Pete > > > > On 13/10/2021 19:12, John Dammeyer wrote: > > I'll agree with Andy here. I have a dual trace older digital scope and > a 4 trace digital that can even decode CAN, SPI and I2C messaging. I > bought a small Digilant PC development kit version for $400 or so to get > UART decoding for a PAN-TILT system that was misbehaving. The add on > module for the scope to do that was $1200 so a no brainer. Haven't used it > since we solved the serial port issues 3 years ago. > > > > But my 4 trace I use all the time. The 2 trace has spent time out in > the shop by the mill but was useless for determining what the issue was > with the out of spec DC servo that only lost steps in one direction and > never the other. The G-54 zero crept in one direction resulting in the > center drill peck holes being in one place and then a bit later the drill > bit for those holes not lining up. > > > > In a noisy shop environment just getting the scope to see real data as > opposed to the noise it picks up may be impossible. I saw that at a > Siemen's plant in Regensberg Germany back in the early 90's. We scoped a > CAN bus and could barely see the signal on the differential pair yet the > system operated flawlessly. Just couldn't find the right ground or > whatever... > > > > So the money spent on a scope may not be worth anything. > > > > John > > > > > >> -----Original Message----- > >> From: andy pugh [mailto:[email protected]] > >> Sent: October-13-21 3:22 AM > >> To:[email protected]; Enhanced Machine Controller (EMC) > >> Subject: Re: [Emc-users] Fwd: Rogue Index Pulses > >> > >> On Wed, 13 Oct 2021 at 11:13, Peter Hodgson<[email protected]> > wrote: > >> > >>> I'm watching a couple of Oscilloscopes on eBay so might take the > plunge. > >> I am going to go against the consensus and suggest that if you don't > >> already have an oscilloscope, and don't know how to use one, then you > >> might not find it much help. > >> > >> I certainly got nowhere trying to use one to track down false > >> triggering of limit switches. And I have owned a 'scope for decades > >> (though not used it more than a few times a year) > >> > >> -- > >> atp > >> "A motorcycle is a bicycle with a pandemonium attachment and is > >> designed for the especial use of mechanical geniuses, daredevils and > >> lunatics." > >> � George Fitch, Atlanta Constitution Newspaper, 1912 > >> > >> > >> _______________________________________________ > >> Emc-users mailing list > >> [email protected] > >> https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > > Emc-users mailing list > > [email protected] > > https://lists.sourceforge.net/lists/listinfo/emc-users > > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
