Eric H. Johnson wrote: > I am running into a small problem with dropped / excess steps using the > m5i20 board and Hostmot2 driver. The problem appears to be with the 50 pin > cable connecting the m5i20 with the TB. The quick form of my question is, > are there any recommended cables / manufacturers of cables to use with the > Mesa boards in the 18" to 24" range? > > The longer explanation is as follows: > > With the Hostmot2 driver and m5i20 board, the stepper signals come off the > P4 connector, the farthest connector from the point where the cable exits > the computer. One loses about 8" just exiting the computer, so with an 18" > cable, there is only about 10" left to get to the TB. Due to the panel > layout, I really need a 24" cable from this connector. > > I have tried several lengths of ribbon cable, and one rounded cable. The > best performing cable is the 24" rounded (it ought to, it cost about $20). I > need to run about 20 cycles the length of the X axis to lose a quarter turn > of the motor (i.e. drifts towards the min limit). The 18" flat cable will > lose it in about 4 cycles. The stepper motion starts to get rough with a 30" > flat cable, and anything longer (I was testing with a 54" cable) is so > unstable as to basically not work at all. One odd thing is that with the 18" > flat and 24" rounded cables, only the X axis demonstrates this problem, if Y > is having any problem, it is so small that I have so far not been able to > detect it. > > Past the TBs I am using Belden low capacitance cables with individually > twisted pairs, foil shield and drain, plus an overall shield to connect the > stepper signals to the drives. This part appears to be working fine, as > nothing changes if I swap things around past the TBs. > > Any ideas or recommendations?
I doubt that the ribbon cable between the FPGA board and the amplifier daughterboard is the problem. Based on Peter's recommentation, I'm using 5' long flat ribbon cables. Each cable has just two connectors (none in the middle). One connects my 5i20 to my break-out-board for the steppers; the other connects the 5i20 to my 7i30 servo amp. This setup is totally reliable for me here, but maybe my test setup/environment isnt as difficult/noisy as what you're working on. Are you sure it's noise in the cable, rather than, say, stepper timings or something? (Every human being should be issued an oscilloscope at birth.) -- Sebastian Kuzminsky ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
