I'm wondering, Latency might not even matter if the commands are buffered, just so long at the data gets there before some deadline. I don't know how the protocol works. Look at the example of streaming music. As long as the buffer never goes empty there are no dropouts. For a machine tool that runs a pre-written programs a slight delay would not matter. For a machine that interacts with the real-world environment, latency does mater
Then the other thing about latency is that what matters is when the LAST bit gets there not when the packet is sent. As an example, let's say a parallel port is sending data at 1M bytes per second. It takes 100 uS send 100 bytes. Ethernet is 10X faster and sends the same packet in 10uS. Even if the Ethernet has a latency as bad as 50uS, the over all latency is better. Looking at the nearest Linux based PC I see it has a fixed 15uS delay with Ethernet. Even with short packets the Ethernet should win the race.. It depends on the packet size. Again I don't know the protocol. On Sun, Apr 22, 2018 at 1:13 PM, John Dammeyer <[email protected]> wrote: > I agree! I've always assumed that the Ethernet real time side of things > is > dedicated to the machine. If you also want transfer files to it a second > port would be required. What I like about the Ethernet control side of > things is the PC doesn't need to be really close to the control > electronics. > > John Dammeyer > > > -----Original Message----- > > From: Kenneth Lerman [mailto:[email protected]] > > Sent: April-22-18 10:39 AM > > To: Enhanced Machine Controller (EMC) > > Subject: Re: [Emc-users] Mesa choices > > > > I wouldn't want to share an ethernet between real time control and ssh, > > file transfer, ... > > > > Either buy a PC with two ethernet ports or just add a second cheap one > > connected by USB. Then use the USB one for all of the usual stuff where > > there is no real time constraint. > > > > Ken > > > > > ------------------------------------------------------------ > ------------------ > 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 > -- Chris Albertson Redondo Beach, California ------------------------------------------------------------------------------ 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
