All of Peter's advice sounds great. My only added advice would be to quantify the problem before you solve the problem. The first thing I'd do is get a digital storage oscilloscope and observe all of the signals - motor power, Hall effect signals, encoder signals, any control signals.
It's a great help to see where the problem is and quantify it so you know what you're trying to fix. It also helps you to know when you're finished fixing the problem. We can't see electrical signals. If you don't see the signals on an oscilloscope, you'll have no idea if it's so noisy that it's on the edge of failing. Your goal should be a robust system for your customer. If you sprinkle magic fairy dust and ferrite beads around until it starts working, it's more of an art than a science and you may be on the edge of some other failure that can cause scrapped parts, downtime and unhappy customers. 99% reliable may be good enough to pass a runoff test if you're lucky, but it won't be good enough to run production. I generally verify signal integrity with an oscilloscope as I'm integrating each subsystem. I'll hook up the encoder and spin the motor by hand and look at the encoder signal without power to the motor. Same with the Hall effect signals. Then I'll look at the analog control voltage to make sure it's not noisy. Then I'll look at the motor power as the motor is running. Then I'll look at the encoder and Hall effect sensors as the motor is running. Then I'll repeat that for the next axis. When all axes are running, I'll look for cross talk, to see if the Y axis motor is causing any noise on the X axis encoder, etc. You'll probably end up doing all of the stuff that Peter suggested anyway, as they're good design practices, but I'd prefer doing things in a systematic manner and verifying all signal integrity, not on the bench back at the shop, but on the shop floor in the final configuration. To me, it's part of truly understanding a system. It's one thing to have a block diagram in your head of how a basic configuration is wired. It's an entirely different thing to understand the subtleties of noise, signal timing, rise and fall time on square waves, etc. It's the second half of my education. Knowing why a problem occurred before fixing it is a good way to learn to avoid problems in the next installation. You'll learn how close is too close for motor leads and encoder leads. Next time, you'll run shielded cables instead of running unshielded cables, having unpredictable behavior as the customer is watching, and then ripping out the unshielded cable and replacing it with shielded cable. Seeing the signals on an oscilloscope is the difference between leaving when a job is finished and thinking that it seems to be working properly, as opposed to knowing that it's working properly. On 01/08/2013 10:29 AM, Peter C. Wallace wrote: > On Tue, 8 Jan 2013, Viesturs L?cis wrote: > > Forgot to say: the Hall wires should also be shielded > and since they are single ended you may need to add a > .1 uF capacitor from each Hall pin to Gnd at the 7I39 end > of the cable > > > >> ------------------------------------------------------------------------------ >> Master SQL Server Development, Administration, T-SQL, SSAS, SSIS, SSRS >> and more. Get SQL Server skills now (including 2012) with LearnDevNow - >> 200+ hours of step-by-step video tutorials by Microsoft MVPs and experts. >> SALE $99.99 this month only - learn more at: >> http://p.sf.net/sfu/learnmore_122512 >> _______________________________________________ >> Emc-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-users >> > Peter Wallace > Mesa Electronics > > (\__/) > (='.'=) This is Bunny. Copy and paste bunny into your > (")_(") signature to help him gain world domination. > > > ------------------------------------------------------------------------------ > Master SQL Server Development, Administration, T-SQL, SSAS, SSIS, SSRS > and more. Get SQL Server skills now (including 2012) with LearnDevNow - > 200+ hours of step-by-step video tutorials by Microsoft MVPs and experts. > SALE $99.99 this month only - learn more at: > http://p.sf.net/sfu/learnmore_122512 > _______________________________________________ > Emc-users mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/emc-users > > ------------------------------------------------------------------------------ Master SQL Server Development, Administration, T-SQL, SSAS, SSIS, SSRS and more. Get SQL Server skills now (including 2012) with LearnDevNow - 200+ hours of step-by-step video tutorials by Microsoft MVPs and experts. SALE $99.99 this month only - learn more at: http://p.sf.net/sfu/learnmore_122512 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
