Lots of over kill listed in this thread. First: Don't use a PLC for this! This is supposed to work even if the electronics is gliched. The system is really simple and ultra reliable if you keep silicon out of it.
It only takes a hi-reliability multi pole relay and a high reliability momentary start up switch. One NO pole of the relay is wired in series with its own coil - this same line pass through NC contact of the E-stop switch and NC contacts of every other safety contact. A start up switch closes the relay - and then it keeps itself closed as long as non of the safety contacts, open or a power dip. The other poles energize the circuits you want to drop out on E-stop. The key feature of this setup is there is just three critical devices - the relay, the start up switch and the wire (this wire should make a loop, never crossing itself where it could get shorted and bypass the interlocks). If any of the interlocks fail(shorted on), the others still work. There is no limit to the number of interlock contacts you can add in series. Some interlocks to think about: Output of a "good AC power detector" Output of "good DC power detectors" Output of a Watch dog timer Multiple E-stop buttons - never be out of reach of one. -------------------------------------------------------------------------------- Karl Schmidt EMail k...@xtronics.com Transtronics, Inc. WEB http://xtronics.com 3209 West 9th Street Ph (785) 841-3089 Lawrence, KS 66049 FAX (785) 841-0434 The State is that great fiction by which everyone tries to live at the expense of everyone else. -- Frederic Bastiat, French economist of the 19th Century -------------------------------------------------------------------------------- ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
