On Thu, 14 Sep 2017 04:03:30 -0400 Gene Heskett <[email protected]> wrote:
> On Wednesday 13 September 2017 12:50:15 Nicklas Karlsson wrote: > > > > > No SPI over long cable. For long cable RS422 will work, there is a > > > > tradeoff between cable length and speed. > > > > > > Poor wording on my part. I had, once the terminations are sorted, > > > visions of a 3 to 4 foot cable, defined as a long SPI cable. > > > > > > Right now, terms are not well characterized on either end and it > > > takes some loading trickery to make a 6 inch cable work. Bertho and > > > I spent some time optimizing it to get 30.5 megabit one way, and 25 > > > megabit the other direction. And its now working well to a Mesa > > > 7i90 with a 1" cable. > > > > Ethernet shielded twisted pair four pairs like this: sck+gnd, > > miso+gnd, mosi+gnd, chip select + gnd. Or flat cable with a gnd cable > > between each of them. Or of course Ethernet if available. > > No, the tcp is too slow, much latency. For TCP resend function to make sense there must be enough time to resend packet. > However, the above scheme, made into ready-made hardware and a matching > rj45 socket signal assignment on those mesa cards that can support spi, > like the 7i90, ... Ethercat chips are available with SPI interface and I concluded then distance is short enough and data is sent between it might be a good choice to skip the Ethercat chips but I might be wrong. Nicklas Karlsson ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
