Transpose Ladder logic via Rslogix5 to ST

[davesbs]

What i would like to do is transpose some filter routine ladder logic to Structured Text. Not really sure how to attack this one because its not something I can put into if/else statements. I have three parameters to pass to the filter routine

a. value to filter
b. previous filtered value
c. time constant of the filter

once passed to the filter the filter exponent and coefficient is calculated and a output filter value is returned.

The rslogix5 ladder used SBR to pass the inputs. I figure all i need to do is define a UDT for the filter float inputs.
UDT = FilterFlt
Member Names = FilterValueActual
FilterValuePrevious
FilterTimeConstant

Am I on the right track?

 

[CroCop]

If you're using a ControlLogix PLC, then yes. If you're using the PLC5, no.

The subroutine is very easy to set up, just put JSR in the help file & it will all become clear.

 

[davesbs]

I'm using ControlLogix via RSLogix5000. The ladder is from an old RSLogix5 .RSP file. I need to transpose the ladder logic from the .RSP file to Structured text in RSlogix5000.

So I take that as a yes as far as me being on the right track.

So I built the udt's, the ones mentioned above. should I create the tags used to calculate the filter outputs in the same area?

 

[davesbs]

I mean udt members not tags

 

[CroCop]

I would make a spare UDT to pass the data onto, & I would declare it as a local variable.

So far, it looks like you've got a handle on it.

If you'd like, I can post a RS5000 subroutine code.

 

[davesbs]

Please do... That would be great.. Thank you very much for your help.

 

[CroCop]

Here is a basic stripped down idea of what I down on a crane with 5 axises that are manually controlled by basically the same things, & output the same things.