PLC: If Then Else inside Function Block

Question

I'm trying to learn by programming for a Bosch/Rexroth MLC. I wrote this sequence, but I'm not sure if there's a better way to do things.

Pseudo-code would look something like this:

wRunningCount=300
wStandstillCount=150
wCount
zeroSpeed
IF zeroSpeed THEN
    wCount=wStandstillCount
ELSE
    wCount=wRunningCount
FI

But I want to move this functionality into function blocks. (Already have a TON that will receive the wCount)

Right now I have:

                  __MOVE____
       zeroSpeed-|EN    ENO|-
wStandStillCount-|_________|-wCount


                  __MOVE___
      zeroSpeed-o|EN    ENO|-
   wRunningCount-|_________|-wCount

Is there some better way to do this?

Answer 1

depending on how you want to initialize your variables you can do this

Otherwise there is not better way to do it then you are right now.

Answer 2

Most 61131 implementations will have a "SEL" block that should do this fairly nicely...

            __SEL__
zerospeed  |G     Q|wCount
           |       |
wrunning   |IN0    |
           |       |
wstandstill|IN1    |
           |_______|