Stage programming on Directlogic 5

After reading all about the advantages the Stage programming could have, finally I come to the practical question: where are the stage instruction buttons?

Never mind, I found them in the Box button.

Alec,

If you find some way to make the Direct Logic Stage relays useful, please tell me how you did it.

For the times I tried it, I always regretted it, and eventually went back to just creating my own stage relays with regular old instructions (for which I have total control).

Just as some find ladder logic cumbersome and would rather use Statement List or Function Block or other control formats the Stage Programming (RLL+) either resonates with your method of control or it doesn't. It happens to fit mine very closely. For me the Stage encapsulates the 'do this until that happens' philosophy of control. Any conditions which must be monitored at all times can either be placed before the first stage or in a Stage which is enabled then never turned off.

You may have already seen them but my feelings on the matter are stated here.

I have really come to like stage program with AD. It really helps me break down a large control problem and keeps it organized. I have used this type of programing on many control problems to tie different machines together which use for example the same coolant filtration system ect. For large programs its very useful once you get used to it. Just remember if the stage is not active then the rungs wont be scanned so if you have something that needs updated every scan keep it in a ISG stage or outside of the stages period.

Hi Lancie,

By creating your own stage relays, I 'm sure you know the advantages of stages better than i do. But I included all stage instructions into a short program which might be useful for newbies. it is attached but please notice S0 may not be able to activate again if C3 has been toggled.

I like the calling blocks function because its like a call-a-sub function in VB script and the stage remains active; but i prefer to see each stage or block in a separated window.

AlecTek said:

but i prefer to see each stage or block in a separated window.

Click to expand...

Click on View, there will be a stage view option. You can also view another window of ladder by "dragging down" the little bar just above the "scroll up arrow".

Critique below:

Descriptors?

I don't see a coil for C0

You do not need to use the SP1 contact inside stages if it's the first rung inside a stage.

C0-3 is just for the toggle input, you can use X0-3 instead.

The stage view sometimes not working well. But I don't know why the other window (displaying zone) is always empty to me.

"You do not need to use the SP1 contact inside stages if it's the first rung inside a stage. "

Your right, I just feel safer in that way.

I too, like Bernie am a great fan of stage programming. But in my case it's with Mitsubishi PLC's.(FX series)
It sounds just like DL5's methods with none active stages not being scanned.
I took a long time to practice and learn this method and iron out all the nuances of it and it pays off reguarly.

I see a lot of people not liking this method and wonder why. If you take the time it is solid and very helpful for later alterations.

Only recently I visited an old program of mine written this way that had run beautifully for years. It was a conveyor system that marshalled mattresses coming from 2 directions into a wrapping machine.
It queued them and rotated the ones that needed it into the wrapper.
Then they bought and installed another wrapper so that the matresses would be shared between the 2 wrappers.
This involved a few more conveyors linked to the old system.

With the stage programming already done, it was so easy to add extra stages to marshall the mattress's to the correct destination using the old stages already programmed.

One of my biggest tips on programming this way would be - to make each stage small.
What I mean by that is dont have too many actions in one stage until the next is activated.
This makes it so easy to troubleshoot and make later alterations

I guess stage programming is developed to make ladder logics structural, but I don't know why the program and/or the programming interface doesn't look like structured at all. I 'm not a fan of it yet.

Stage programmings works well for those applications that can be defined step by step

Machine control requires a flow chart or sequence of steps. Most of these sequences can be generally described as do this and wait for that and when that happens go do the next thing. The stages or steps are a natural for this kind of programming. In IEC they have SFC. Our controller almost forces you to use a sequence of steps/stages and transitions.

A lot of our tech support calls are really application calls where the user hasn't even defined a flow chart or sequence of events. It is hard to help these guys except to suggest something. Once the sequences of events or flow chart is written the programming goes quite quickly. The stage or step programming organizes the program for you and will take care of problems like race conditions if you follow the rules. I have seen too many people write disorganized machine control code without the aid of stage programming or a similar method. They often have race conditions.

If you are doing continuous tasks like temperature PIDs then step/stage/SFC program is not what you want to use.