On Thu, 1 Dec 2011 12:43:52 -0600 Thomas Powderly <tomp4...@gmail.com> wrote:
> On Tue, Nov 29, 2011 at 9:11 PM, Jon Elson <el...@pico-systems.com> > wrote: > > Kenneth Lerman wrote: > >> Hi Viesturs, > >> > >> For a cable to be good, it is necessary that all the signals have > >> low end to end resistance, but that is not sufficient. > >> > >> You should also check that no two signals are shorted to each > >> other. (But you probably know that.) > >> > > Also, for EPP to work, the crosstalk between certain signals needs > > to be small enough that it doesn't cause false triggering of > > circuits. The EPP mode has data and address strobes and an > > acknowledge signal from those strobes, as well as a reset signal > > and a read/write signal. At least these 5 signals are really > > critical, and any crosstalk on them from the data lines or other > > signals will cause corruption of the data. I have test programs > > that are used with my boards to detect faulty communication so that > > changes can be made until the communication is reliable. > > > > A 20" cable made from straight ribbon cable may be long enough to > > cause crosstalk or reflections, due to the impedance not being > > matched. I have to use cables made specifically for IEEE-1284 use, > > they have "IEEE-1284 compliant" printed on the cable jacket. Many > > of my customers try to use some old cable they have on hand, and it > > almost always causes problems. I have made some ribbon cables about > > a foot long, and they seem to work. > > > > You can't detect these sorts of problems with a DVM, you need an > > oscilloscope, at least. > > > > > > Jon > > > Jon, > Hello, > The IEEE-1284 complaint cables seem to have centronics connectors on > one end ( not db25 ) > so i looked for compliant cables with db25 m-f ends > a little googling found they seem to be called 'IEEE-1284 compliant > extension cables' > typified by the thicker cable and pricier ( often twisted pair which > is good ) > > thanks for the tip > TomP Early on I ended up making a converter from Centronics to DB-25 so I could communicate with a ppmc. Finally I made a very solid mount from the chassis my ppmc motherboard was mounted on to the motherboard. From that time on the connection was solid; if I ran Jon's comm program and got clean results then it was going to be that way forever. :-) Mpre than one way to skin a cat! Dave > ------------------------------------------------------------------------------ > All the data continuously generated in your IT infrastructure > contains a definitive record of customers, application performance, > security threats, fraudulent activity, and more. Splunk takes this > data and makes sense of it. IT sense. And common sense. > http://p.sf.net/sfu/splunk-novd2d > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ All the data continuously generated in your IT infrastructure contains a definitive record of customers, application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-novd2d _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
