Does anyone have an example or app note of how to use Digital Inputs 1 or 2 on a Power Flex 700S with Drive Logix for HIGH SPEED COUNTING?

This input will be wired to a prox switch and will ultimately be averaged over time to get the velocity of an idler roll.

Sorry, I didn't design it, I'm just trying to make it work! And I don't have the time to wade through the endless (mostly useless) RA documentation.

 

I write some of that "mostly useless" stuff, but fortunately I have thick skin. You're in it pretty deep, friend, if you have a complex product like the PowerFlex 700S drive and no time to read and no chance to design.

The bad news is that the Digital Inputs on the PowerFlex 700S aren't designed to be pulsetrain or frequency-counter inputs. They have about 34 different functions, as listed on page 3-75 of the PowerFlex 700S Phase II Control User Manual (RA publication number 20D-UM006). But none of those functions are "selectable period average pulsetrain input".

The encoder inputs on a PowerFlex accept 5/12VDC inputs and you can configure the encoder to be Channel A only, and can set up some filtering (might not be enough) to handle the proximity switch. The encoder configuration is on page 3-31 of that same user manual. I've never seen somebody hook up a prox switch to an encoder input successfully, but it might be worth looking at if your prox switch happens to be 12V and super-high-speed.

Because this is a 700S drive, you have the option for DriveLogix, which has local 1769 I/O modules you can hook up. You could run a regular DC input and average it yourself (depending on it's speed), or you could use an expansion 1769 High-Speed Counter card, then pass that parameter to the drive as a velocity reference.

Another option might be to use a frequency/analog converter like Calex to get an analog value from your pulse train. It's an imprecise way to implement a speed follower, but I suppose it's possible.