Function Blocks EN & ENO - used for executing in a sequence?

[SCADA_Dude]

Reality Check Question:

For a Function Block Diagram, can I safely assume that a function will not output ENO until it has completed execution? I am assuming that by stringing the EN-ENO-EN-ENO-EN I can establish an order of execution as if they were in order in Structured Text?


I hope this is the case, or I am missing the point of EN ENO.

 

[L D[AR2P#0.0]]

A better description of ENO is block result. When a function executes, the block result will be set to true or false depending on the processing inside the function. It does not indicate that a function has completed execution.

 

[RollingPin]

Why would you want to string them up in the first place? Like in ST, even with FBD, what you see is what you get. The sequence of FBs that you see in your programming environment is the sequence in which they get executed. Which software are you using?

EN only enables or disables execution of that FB and ENO := EN. If you string an ENO from one FB (say 'A') to EN of another FB (say 'B') and if B is placed before A in the FBD, B would still get executed only in the next execution cycle after A was excuted.

 

[SCADA_Dude]

I am using Unity Pro XL 3.0.

How do I know the order that the FBD will execute? Is it left to right then down to next row? Does it completely evaluate the first block before moving to the next one?

Thanks

 

[L D[AR2P#0.0]]

My comments only apply to Siemens S7 300/400 programming so please ignore.

 

[SCADA_Dude]

I found an option on the FB that says "execute after" in the properties menu, with a drop down of all the other FB's on the diagram.

Problem solved! Thanks everyone for the help.