Has anyone produced a Concept DFB or has produced function block style code to replicate the functionality an Analog Transfer block (Bailey FC 9). This function block selects one of two inputs depending on a boolean input which is then transferred to the output (same as the SEL block in Concept). However the Bailey FC also has two configurable specs which are time constants to provide smooth transfer in both directions. When the transfer block changes the input selected, the output changes to the new level exponentially over a period of five time constants when the transfer time constant specs are set to a value other than zero. After five time constants, the output tracks the selected input.

 

Hello;
I was solved partially it some years ago(I did not need reproduce completely the Bailley function) using KOPor FUP with S7. So if want to contact me at autcon20ATyahoDOTcomDOTar
we will can discuss this point. I will need some time to search on my old database the older solution.

Best

 

It's been at least a decade since I did any Bailey programming and a few years since my last Concept IEC program, plus I don't have a reference for either one anymore. Here's my two cents worth, anyway.

Try putting the lag filter block after the SEL output. After five time constants, an exponential filter will reach 99.3% of the input step change. Use two timers, one enabled on select input high and the other enabled on select input low, and 5*tc as the preset. OR the Q outputs and use the result to force the filter to track mode when the timers are done. That will keep the filter from affecting the in/out transfer after the transfer time ends.

Mike