Variable Frequency Drives (VFD) very useful advanced setup

Hi, y’all, and howdy from Texas!

We are here again to tell you about another automation adventure we were part of last week.

We commissioned several production lines with some archaic setup (considering what we have nowadays…), utilizing potentiometers, LCDs, point-to-point controls, etc…

The devices used were: Powerflex 525 drives and Compact Logix PLCs.

As most automation professionals know, you can easily use a 10K potentiometer, utilize the analog output from the drive to reflect your speed in a display or something similar, however, from a specific request from the customer, we would’ve need to scale the speed frequency according to the cuts/min and “clamps” added to the minimum/maximum frequency span on the drive itself.

Even though the drive was hardwired, we could connect or bring the VFD into the PLC, and start manipulating the data by introducing them to the PLC via ethernet/IP, and that’s what we did!

The first step was introducing data from the drive and sending it out as well, so to scale the speed and write the correct value to the LCD, we had to use:

Parameter 88 – Analog Out Sel – which will define how your analog output will act, we select value 22, which corresponds to “setpoint”

We used This parameter to send the correct value to the LCD, and the way we initially worked was reading the output frequency but, down the road, we encountered another issue when we had to use the “JOG” button.

As mentioned above, since we “clamped” the min/max speed limits, every time we pushed the jog button the drive ramped up to the minimum value and did not respect the jog speed set to the drive’s associated parameter.

Now, all of a sudden, there was a need to figure out a solution to make these machines work as they did before the changes.

We then remove the clamps and build them in the logic.

We introduced a new parameter 360 – Analog In 0-10V, which is Mr. Potentiometer, and used to command the speed by scaling the values (0-1000) to the frequency command and soft clamp the min and max speeds.

At this point, we were able to build two types of situations, one that was “normal mode” and the other “jog mode”:

I know this is simple code at the end, but here we want to focus on how a VFD, in particular a Powerflex 525 in this case, can help you accomplish what you need without adding more hardware, but you need to get a little bit creative for sure!

Because, to be honest, our first thought was to add more cards, more crap, more more!

Well, sometimes you can do more with less!

Let us know what you think about this post, and let us know if you have a challenging project or issues that you can solve, we thrive on them!

The future of automation looks Bright! Stay tuned for more and follow us on Youtube, TikTok, Instagram, and of course Linkedin!