"Tom Gardner" wrote in message
...

On 4/25/2012 6:27 PM, RogerN wrote:
"Tom Gardner" wrote in message
snip
Just some ideas.

RogerN



Yep, that's the cycle, it can be even simpler without the added safety. The
HP cycle end is a limit switch and the operator can hit a switch that's in
series with it and reset the machine. No need to jog it or troubleshoot,
we get about 1 in 2,500 that something goes wrong. I certainly like using
the timers though!


You can get the controller that you choose and write the program for it and
start learning and testing.

You can parallel all the inputs and outputs with memory bits.

After your control program, write some rungs that simulate the machine
operation.

Such as: If Cylinder_Extend_Valve start ~3 second timer, when timer done
turn on Cylinder_Extended_switch. That way you can "press the start button"
in simulation and see that the entire sequence works, before ever touching a
wire on the machine. If you have spare buttons you could even wire in your
2 hand trip control, if the timer is right it's easy to operate but
difficult to fool.

The difficulty I had in getting into ladder logic from other programming is
you have to program the sequence by knowing all rungs are scanning all the
time and the sequence is controlled by conditions like step 1 done enables
step 2, step 2 done enables step 3...

RogerN