On Wednesday 22 May 2013 21:43:01 Jon Elson did opine: > Gene Heskett wrote: > > Thats pretty decent Jon. Sounds like the best solution without > > depending on pure unobtainium parts too. > > It has to be! I'm selling these servo amps for $125. Not much margin > on that! > > Jon I know, and I've been trying to figure where I might be able to use one of them, but the time & place hasn't came together yet. I'm stuck in a step/dir world here, and the price of admission to go from there to a 50khz pwm servo means the first ticket is about 2x that $125.
So I use the controller that is in the machine, with a PMDX-106 or a C41. Both of those however aren't capable of doing a safe reverse drive, simply because the reverse is dependent on the PWM presence. So I guess I get a separate relay board and re-route the reverse signal thru it. To me, its a huge mistake to have the reversing relays drop out when the PWM stops. To have a 1hp motor turning 7g revs in reverse, click the stop button, the driver is slow to detect the D/A drop, the reverse relay drops out 100 milliseconds later while the motor is still turning 6.5g revs, and the filtering in the D/A to the controller is still telling the controller to output 50% power, and the ensuing excitement will not contain the smoke & broken mirrors when the controller discovers the motor is turning backwards at 6500 revs. The scr's in the controller will fail to protect a $4.00, 9 amp circuit breaker from opening. So, go get a relay board with two relays on it because one is never enough, and use one of them as the reverser because I CAN control it from some custom delay logic in the .hal file. But ATM I am sawing up (on my table saw) a 1/8" thick side panel from a wrecked UPS van to make a swarf proof (I hope) housing for the motor & electronics, which will be sticking out the back of the lathe about 9" once its all mounted. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> Don't shout for help at night. You might wake your neighbors. -- Stanislaw J. Lem, "Unkempt Thoughts" A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. ------------------------------------------------------------------------------ Try New Relic Now & We'll Send You this Cool Shirt New Relic is the only SaaS-based application performance monitoring service that delivers powerful full stack analytics. Optimize and monitor your browser, app, & servers with just a few lines of code. Try New Relic and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_may _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
