Well test it and commit you results back??? On Mon, 8 Jul 2019, 03.38 justin White <blazin...@gmail.com> wrote:
> So another thought is that since there is a Tx enable in the hm2 module > it's obviously there for a reason. rs485 is always emphasized but rs485 is > mentioned in alot of cases as well. In the case of an 8i20 it includes > jumpers to enable bus termination resistors. So I'm wondering if using the > Tx enable on the driver would technically make it rs485 so you could run > multiple devices like 8i20s or smbl drives on one channel. There could be > other considerations like latency issues or something, just curious if that > would work. > > On Sunday, July 7, 2019 at 8:36:39 PM UTC-4, justin White wrote: >> >> >> >> On Sunday, July 7, 2019 at 2:16:22 PM UTC-4, Charles Steinkuehler wrote: >>> There's good info in the data sheet for that part: >>> http://www.ti.com/lit/gpn/thvd1451 >>> ...which is an RS-485 transceiver (RS-485 is the same electrically as >>> RS-422, but the driver can be switched off). >>> RS-485 is a "multi-drop" protocol, and supports multiple transceivers. >>> Typically, the end nodes will have termination resistors populated >>> and the devices in the middle on the cable will have the termination >>> disabled. See figure 32 (page 22) in the data sheet. >>> PCW said it's straight RS-422, not RS-485. That means you only have >>> two devices making each device an end point, so add termination to >>> both ends. >> >> >> That's kind of unfortunate because you'd need a separate channel for each >> device. Now my head is spinning again because my encoders and stepgens are >> differential recievers/drivers so I could technically pretty much just >> repurpose one of each and get a couple of channels out of one set of >> connectors. I didn't put any impedance control or TVS on them but now I'm >> thinking if I make some accommodations I can just sacrifice encoders and >> stepgens for serial channels. >> >> >> The ESD protection is application dependent, but you might also want >>> a small value series resistor between the THVD1451 and the cable (see >>> Figure 38, page 27 along with the recommend parts list) and see the >>> layout recommendations on page 29. >> >> >> >>> ...but don't sweat the details too much. For a short range (a few >>> meters) point-to-point connection, the ESD and even the termination >>> resistors are not super important. I'd still add them (it's cheap >>> insurance!), but I don't expect you're designing for 1.5 km long >>> cables that need to withstand nearby lightning strikes. :) >>> That said, spindle motors can throw off enough ESD to cause problems >>> even with differential signals, which is why you want _something_. >> >> >> I just whipped the drawing up this morning, I was originally going to use >> a different chip and had a different drawing. Good to know it's on the >> right track though. >> >> tvs and esd are somewhat of a concern since while I didn't really intend >> it, I can pretty much replace the x86 PC and 7i76e on my mill with this. In >> that case I use an 8i20 for my spindle with a power supply that consists of >> some big caps, a couple of SSRs and a bridge rectifier. There's 240v AC >> going into that box 320v DC coming out. While I shielded all cables, a >> little protection on the data lines is probably a good idea. Not sure of >> the performance of the DE10 Nano itself just yet since I just load up an >> Axis config and fire up halshow for the time being. Unless I converted my >> mill I probably wouldn't have an actual machine to run on this any time >> soon. >> >> Every time I think I'm damn near done with it I come up with something >> else to complicate things lol. >> > -- > website: http://www.machinekit.io blog: http://blog.machinekit.io github: > https://github.com/machinekit > --- > You received this message because you are subscribed to a topic in the > Google Groups "Machinekit" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/machinekit/eVhvTnuhblE/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > machinekit+unsubscr...@googlegroups.com. > Visit this group at https://groups.google.com/group/machinekit. > To view this discussion on the web visit > https://groups.google.com/d/msgid/machinekit/6df1fef2-f29b-4019-b58e-0b6492a07be5%40googlegroups.com > <https://groups.google.com/d/msgid/machinekit/6df1fef2-f29b-4019-b58e-0b6492a07be5%40googlegroups.com?utm_medium=email&utm_source=footer> > . > For more options, visit https://groups.google.com/d/optout. > -- website: http://www.machinekit.io blog: http://blog.machinekit.io github: https://github.com/machinekit --- You received this message because you are subscribed to the Google Groups "Machinekit" group. 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