On Saturday 24 December 2016 12:40:43 Bertho Stultiens wrote: > On 12/24/2016 01:20 PM, Gene Heskett wrote: > > If that fails, I'll quit beating my head with a hammer and reset > > this 7i90 to an epp interface and go back to an x86 computer to > > drive it, but that brings up the next $64K question. The big old > > Dell I have to drive it with isn't swarf proof by any means, and it > > will take at least 6 or even 8 feet of ribbon cable to get it far > > enough away from the swarf to be safe from flying chips. Can I use > > a ribbon cable that long with good results? The man page says it > > could be a problem but doesn't say how long is too long. And I've > > no clue if the parport on this old Dell can be made epp-1.9 > > compliant. TBD I guess. > > The achievable length of the cable is usually determined by the cable > loss and the impedance matching of the cable. > > In principle, you can roll out 25m of parallel port cable if you > ensure that firstly, the drive power is sufficient to overcome the > capacitive load of the cable and secondly, that the cable-impedance is > matched either with driver-side series resistors or symmetrical > termination on each side. (*) > > The drive power of most "old-style" parallel ports is enough to drive > 10m of cable. However, the reflections are significant and interfere > with higher frequency signaling (step-signals are fast enough to > suffer). > > The cable impedance is usually around 100 Ohms (maybe 120 for some). > Thus, inserting a 100..120 Ohm series-resistor on each output driver, > just before entering the cable (ideally at the driver output pins of > the driver chip), should be a nice enough match for most cases and > uses. Just be sure that you identify the correct side of the cable > where to insert the resistor. It must be done on the drive-side to be > effective. If you have bidirectional communication on a wire, then it > becomes a bit more difficult. But that usually does not happen on most > EPP setups and the inputs and outputs are perfectly defined and > constant. > > (*) I am ignoring common-mode and ground problems here, just as > shielding. If your environment is balanced enough and not EMI > infested, then you should not see too many problems.
Thats encouraging Bertho. If I can beat the parport into epp,v1.9 mode, we'll try 10 feet. EMI could be a problem as the power goes up to the VFD, and the VFD drive comes back, thru the same length non-shielded plastic bx. That isn't going to be common with the ribbon cable, nor with the isolated 4 wire from the spinx1 to the vfd. I won't know for sure till its been tried. :) or :( But this is Christmas Eve. So almost nothing will be done till Monday. 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) Genes Web page <http://geneslinuxbox.net:6309/gene> ------------------------------------------------------------------------------ Developer Access Program for Intel Xeon Phi Processors Access to Intel Xeon Phi processor-based developer platforms. With one year of Intel Parallel Studio XE. Training and support from Colfax. Order your platform today.http://sdm.link/intel _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
