Seeing as how we have at least a few people here who really understand pull-ups etc (and I am not one of them)
I did have everything working fine, but then I blew some drivers meddling with things, and when I replaced them I took the opportunity to get a bigger driver for the X/Z axis (what it calls itself depends on whether it is a lathe or mill config file loaded.) Previously I had the amp-enable lines all connected to the same parallel port pin and it worked fine, logic positive. Pin goes high, amp turns o. This was when all the drivers were this type. http://www.motioncontrolproducts.co.uk/pdf/MSD325_stepper_drive_datasheetV2.0.pdf Now I have added one of these drives, but I can't get it to work the same way (I daisychained all the +5 lines together externally) http://www.motioncontrolproducts.co.uk/pdf/MSD542-V2.0_stepper_drive_datasheet.pdf Ideally I would like the amps disabled if the PC is off, and only actually enabled if EMC is running and active. As far as I can see it all should be logic-negative as I had it wired, but it would seem odd to require a current through the opto-isolators to turn the drives off. That does seem to be what the 325 datasheet says, though (The 525 datasheet seems to be complete gibberish) It is no trouble to change parallel port pins if a particular one has useful boot-up behaviour, nor am I at all concerned about having to use negative logic. (I just didn't know enough about source/sink capacity of parallel ports when I built the system in the first place. I currently have +5V from a PSU connected to the three "OPTO" terminals. I think I have the p-port ground pins connected to the 0V of the same CPU, but on reflection I am not totally sure... I think I might have a half-witted arrangement where p-port ground is not connected to 5V ground, but the 0V lines of all the PSUs (Independent 5V, 12V and 30V ones) are common. What I possibly should have is the 5V ground connected to the P-Port ground (it only actually drives opto-isolators and reflective opto limit switches and could almost certainly float independently) and the other PSU grounds connected to chassis ground. Currently I can't turn off the MSD542 and one of the MSD325 drivers keeps randomly dis-enabling, so I need to do something slightly cleverer. I would have liked to have linked the enable optos in series to reduce the p-port load, but I don't think that is possible with the internal resistors and the internally-commoned +V on the 325 optos. -- atp ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
