On Friday 08 May 2020 11:16:21 dave engvall wrote: > HI all, > My ancient Acu-rite III DRO has gone flaky. I ordered one off the > following link.
Some of those older devices used a light bulb that slowly got black, and a new light bulb fixes them right up. > https://www.ebay.com/itm/2-3-Axis-Digital-Readout-DRO-TTL-Linear-Glass >-Scale-Encoder-for-Milling-Lathe-US/383318755364?_trkparms=aid%3D111000 >6%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D226424%26meid%3Dcfa3ce45df72 >4f6caf6f3f9e3f504aca%26pid%3D100005%26rk%3D2%26rkt%3D12%26mehot%3Dpf%26 >sd%3D143473346840%26itm%3D383318755364%26pmt%3D1%26noa%3D0%26pg%3D20476 >75%26algv%3DSimplAMLv5PairwiseWebWithBBEV2bDemotion%26brand%3DUnbranded >&_trksid=p2047675.c100005.m1851 > That one is plain ttl, Dave, and can drive a mesa card straight in, at its resolution I would bypass any opto's as any usable speed would overrun the opto's. Power it, and ground it to the mesa card, do not ground it at the machine. Ground the machine of course but use a separate wire back to your star ground bolt. > The instructions give two possible connection patterns: both for A+, > B+, gnd and +5v. No instructions for A+, A-, B+, B-, gnd and +5v. No > joy. An internal autoresetable fuse saves idiots from themselves. I > emailed the vendor and got back a 'yes we have no bananas' type > answer. > > "Hi David, thanks for your shopping in our store. > So pleased to serve for you. > Yes, it's no need to do that without having to use opto-couplers to > isolate the connection. Yes, we have no bananas is a perfect description, wasting an otherwise perfect email. > Best regards, > Ebay seller-tradeparts-shop" > > I'm still convinced that I need the opto's but thought I'd bounce > this off the list. > BTW - it works fine with one of their scales. Everytime I encounter opto's I need to reach for the excedrin. The Omron encoder I bought to be installed on the back of my PMDC spindle motor came with low voltage differential outputs. But the mesa card it was to hit had single ended needs. I found some $2 rs485 transceivers that could be wired as omni-directional on ebay and fed the A+ and A- to the 485 input, and fed its rail to rail output by way of a bob to the single ended 5i25 inputs, ditto for the B+ and B- lines. Worked up to about 300 rpms then went berzerkerz, it was too fast for the opto's. Ripped them out, works to 3 grand at the spindle now. To put that in perspective I wrote some hal code to measure the effective ppr of this cobble job, where A/B comes from the encoder but index from the spindle, and got two scale factors, high gear was a tad over 7k ppr, and low gear was just over 14k ppr. Motor wide open thats not quite 400 kilohertz into the 5i25 encoder. Hasn't missed a lick. > Once I get both types of scales going I will do a comparison against > each other and against Jo blocks and boring machine standards. > > Has anyone else tried these and how did you make it work? As always > thanks in advance. > > Dave > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
