Programmable Logic Controllers (PLC)greenspun.com : LUSENET : Elevator Problem Discussion : One Thread
Does anyone have much experience with PLCs? A small installer is proposing to use a PLC made by Siemans (sp?) to control a 3 car, traction variable frequency, commercial project. They claim that it is equal to or better to the dedicated microprocessor control systems of the big manufacturers (Otis 411, Dover T4 etc.) Any insights?
-- Andrew McGregor (email@example.com), November 27, 1997
if you got the oportunity id ask them to show me one installed somewhere or where there at to get an opinoin from building owner or service man that talkes care of them ......as you all know you get what you pay for... if its like the siemens starters .....it aint gonna be worth a dam!
-- anonymously answered, November 28, 1997
Andrew it can be done. Texas Instrments makes a nice one. An outstanding programmer like Bob Halm at Serge could, starting from scratch, provide a very workable system in a couple of weeks. What will probably happen in the instance you cite: 1st elevator 1 year give or take a few days. 2nd elevator 3 months and the 3rd elevator with dispatching and zoning and all of the rest of the bells and whistles to make the system perform 9 months. If the customers patience and pockets are that deep, great. However with a so called off the shelf system from Swift for example you could have the job finished and be on your way to the bank in 5 months. Yes it could be done, but why
-- Fred Baltes (Elman101@aol.com), November 30, 1997.
Andrew: I am a small medium size installer and will use only PLC controllers. Be surethe installer is using the controller from a dedicated controller manufacturer with a long track record. The advantage to a PLC controller is that you can always use any brand PLC to replace the one in your controller. Not like a proprietary unit that is manufactured for one company i.e. Dover, Otis, Motion Control, or Swift. If you can't get parts for your Seimens PLC then replace it with an Omron, Allen Bredley or Square D. I've used Omron 10 yrs.
-- Jerry Rexer (firstname.lastname@example.org), December 04, 1997.
I have been experimenting with a mitsubishi plc. They program with relay ladder logic. So you could replace a relay logic job with the controller and basicly follow a straight line for a program.
-- Jerome Ferro (Jerry) (email@example.com), March 13, 2003.