[dayglored]

Ah, ladder logic! Yes, indeed... in the mid 1980's I designed industrial process control systems that were intended (in some applications) to replace ladder logic controllers. So we often found ourselves in a position of supporting a customer who had a controller, wanted to replace it with our more general-purpose machine, and needed help converting the ladder logic into the process-control BASIC that was the native language of our box.

It was.... ahem.... [cough]... a "learning experience".

I must ask, what in heaven's name type of application requires 24,000 rungs???

[raybbr]

I must ask, what in heaven's name type of application requires 24,000 rungs???

I used to work in the printing industry. We had one press that had four PLC's chained together, each one had about 16,000 rungs. Depending on the configuration of the press you would use blocks of rungs.

Every function that was automated needed blocks of ladder and functions put together to give the operator control and feedback.

That particular press had TI PLC's communicating with a Unix PC, a data bus and a hybrid computer all one press. It was nightmare especially in the printing environment.

I have been using PLC's for over 25 years. I started out with a 5TI and ended up when the place closed to starting using Step 5 from TI. We also had to know Allen Bradly, Omron, GE and several other brands just keep the machines running. Understanding the nomenclature for each brand was the difficult part.