RSlogix 5000 Sequence Control

[james123]

Hi, I am new on RSLogix 5000 programming. Now I am starting a auto machine project and want to control machine process sequentially. I prefer to use a integer to save step number inside. Can anybody guide me through by showing me a sample program?
Thank you very much.

 

[parky]

I do not have RSL, however, there is no difference to any other PLC in reality, I almost exclusively use an integer as a step sequence, I increment in steps of 10 or more this allows spare values should you need to add an extra step, one of the advantages of using a sequence variable is that you can jump forwards or back with ease.
Here is a sample of a simple sequence but it is done in FBD rather than ladder but should give you some ideas.

 

[Aardwizz]

All sequencers consist of two basic parts: Actions and Transitions.

It's usually best to have some sort of "placeholder" to keep track of where the sequencer is at: an integer representing the current step is good for that, rather than merely driving outputs in some sort of sequential manner. You say you are using an integer, so that's good.

Your sequencer logic will then follow the basic format of:

-[On this step]-----{When these conditions are true}-----(Go to this step)-

Or, perhaps as a sample line:

   +---- EQU --+   START_PB     +---- MOV --+

---|  StepTag  |------| |-------|        10 | 

   |        0  |                |   StepTag |

   +-----------+                +-----------+ 

Elsewhere, or here, you can also add some logic to drive the specific I/O.

   +---- EQU --+       Motor01

---|  StepTag  |----+---( )

   |        10 |    |            

   +-----------+    | 

                    |

   +---- EQU --+    |   

---|  StepTag  |----+

   |       20  |        

   +-----------+  

For troubleshooting, I usually prefer to set a bit, "OnStep##", rather than use the EQU as my indicator of what step I'm on, and put all the
EQU StepTag OTE OnStep##
logic at the end.

This allows me to quickly find what happens on step 75 without having to sift through dozens of EQU statements to find what is holding up that step, and to find what I/O that step is driving. Everything I need to know about step 75 is crossreferenced by OnStep75.

But that's a personal preference.

 

[MarkNightingale]

I always use a Step_Number, and a Next_Step_Number.

Then on the last rung of code, If Step_Number NEQ Next_Step_Number - MOV Next_Step_Number to Step_Number.

That way I can hold or pause sequences easily, if for example there is a fault.

Cheers

Mark

 

[James Mcquade]

Welcome to the forum.
i do not have an example program, but may i suggest the following.
try this example.
from your house, what are the steps necessary to get to work?
write down the basics, then expand, and expand again.
start.
1. did the alarm clock go off? yes, step 2
2. turn off alarm - step 3
3. get out of bed. - step 4
4. i am guessing here go to bathroom......

do you see my pattern?
each step details what you do, the next step requires a permission to be incremented.

other examples are going to the grocery store.
starting a car. - more to it than you think.
regards,
james

 

[Jlandwerlen]

I always use a Step_Number, and a Next_Step_Number.

Then on the last rung of code, If Step_Number NEQ Next_Step_Number - MOV Next_Step_Number to Step_Number.

That way I can hold or pause sequences easily, if for example there is a fault.

Cheers

Mark

I do similar, except I have at the top, before the first step, so I have a one scan delay. That gives the ability to use a step in other programs if necessary.

 

[parky]

Another often used way is a main sequence & a sub sequence but that can get a little messy for coders who are starting out.