Lift logic...

I was watching a series of videos on youtube last night, all related to lifts in buildings- https://www.youtube.com/watch?v=_xjXdjj2m5Q https://www.youtube.com/watch?v=_xjXdjj2m5Q. Very interesting and well produced mini programmes.

Lots of pure relay logic etc, but the part that peaked my interest was a huge spiral sequencer drum, maybe 8' tall and had a selector mechanism that went up and down in sync with the car, very elegant.

That got me to thinking, if it can be done mechanically, how would I program it in a PLC? It had logic that made the rising car skip calling floors if there was one above calling, it would then pick these up on the way down etc, very smart.

The last parts showed modern PLC units which were far less attractive, but apparently more reliable

Check the downloads section. Lancie has posted a 4 floor elevator simulator in AB.

Also next time you have Logix 500 open, check out the SQO command.

the_msp said:

Check the downloads section. Lancie has posted a 4 floor elevator simulator in AB.

Also next time you have Logix 500 open, check out the SQO command.

Click to expand...

Got the download, thanks, will be looking at that.

will also have a closer look at the SQO,

My very first 6-floor elevator simulator was done on a job under pressure, using an old DOS Lotus 123 spreadsheet program (all that was available at the job site). Each relay in the elevator was simulated using relay ladder logic (AND, OR, NOT). That spiral sequencer drum (labeled "Selector" in the spreadsheet) was a problem to simulate in a spreadsheet program. I did it by writing some Macro commands (which are included in the attached Microsoft Excel spreadsheet).

To make the elevator "run", type a 1 in one of the floor or car pushbutton positions, then hit the red "RUN" button. I simulated the door opening/closing by the Xs in the doorway. I think you have to save the file before it will run correctly.