Not too concerned about ASM standards on this particular project. The customer requested that I use the existing extruder's HMI as a template for this new extruder, so that's what I'm doing. It's been a work-horse for over 10 years, and all the operators are very familiar with the layout. So I'm good with that. Honestly, it's kind of fun anyway. I'll be tweaking the layout a little as I add more components.
In my graphic, the expression is no longer being used (although it did seem to work just fine after changing the "disable while writing" to false.). Instead, I used a simple Boolean to Add "2" to an integer that calculates the VFD speed reference in Hz in the PLC program. And at the same time, it triggers a TOF, 500ms timer. The timer's .TT bit activates the "ramp" command to slowly bring the VFD up to the new speed reference value. I'm going to be very conservative in what I'm asking the HMI to do for this first project.