PowerFlex70 Direction

Hey folks.

Quick question about direction control on a PF70.

The control is all over the connection on the 20-COMM-E. Start, Stop, Speed Reference and such.

I'm asked to reverse the direction.

I see that the parameter 190 (Direction Control) is set to 0.

0 = Unipolar control with drive logic.

In the code I see a start bit mapped to bit .1 of the Logic Command Word to make it start. I see them stopping the drive with .0 of the Logic Command Word. All makes sense.

I don't see them writing to bits .4 and .5 of the Logic Command Word making the result = No Command for direction according to the manual.

The odd thing is, in the Logic Status Word, I have coming back a true .2 and .3 bit indicating that I am commanding in the forward direction and running in the forward direction.


My question is, If I'm giving no direction command to bits .4 and .5 of the Logic Command Word, should I still be seeing a forward command in the Status Word true in bit .3 as a default, or am I missing something somewhere, whats making bit.3 true?

I didn't look at the drive wiring as its inaccessible at the moment but the drawings show nothing wired to the terminal section or anything drive control. I was suspicious that here was a fwd input there hardwired that would give back the status bit .3 as true for forward.

I'm used to 525 and PFlex 40. Perhaps I don't have to, but I always will make true the fwd command bit in my programs. This isn't my program in question though.

Thanks for and tips!

I believe it goes in the last commanded direction. If you press the reverse button on the HIM, does it change?

The if you change the direction parameter from Unipolar to Bipolar, you should be able to change the direction by giving it a speed reference with a negative value.

P279(Direction Mask) defines the adapters which could issue direction commands.

Make sure DPI Port 5(20-COMM-E) is set to "1" in the Mask.

If the drive is commanded via communications chances are there aren't any configured and wired DIs except for an eventual "Enable" signal.

The default direction of any A-B drive is "forward", and if no Direction command is issued the drive will run in the last direction it was commanded to run.

I would have to experiment to determine if the "last direction command" survives a power cycle.

If you want an always-Forward application, set the Forward bit all the time, or even change Parameter 190 to "Reverse Disable" instead of "Unipolar - Drive Logic".

I like to jumper the Digital Inputs to DC Command and set them all to "Not Used", if I'm doing all of my control over the network.

Ken Roach said:

I like to jumper the Digital Inputs to DC Command and set them all to "Not Used", if I'm doing all of my control over the network.

Click to expand...

Thank you all for the replies.

I will check the MASK word to make sure that its going to allow my adapter to change the direction.

Ken, you said something here that I'm curious about. (Quoted above)

If you set the DI parameters all to not used, then what benefit is there to wiring them all to the DC command voltage?

Thanks!

It's a belt and suspenders approach to preventing un-intended motion.

Tying the digital inputs to DC Common means that no matter what parameter settings are put into the drive (including a replacement drive with defaults) then electrical noise cannot cause cause an un-intended Start or Direction change.

If the user installed a drive with default DI configuration settings, the STOP(CF) on Digital Input 1 would be False, so the drive would show "Stop Asserted" by the terminal block. A troubleshooter would find all the digital inputs jumpered to DC Common, and hopefully that would make a light bulb metaphorically go on in their head, causing them to take a look at the DI settings, or at my extensive notes in the PLC program comments.

I don't do this because A-B drives are particularly susceptible to induced voltage on inputs; they aren't. I do it because I want to be able to eliminate discrete input wiring as a theoretical cause of a malfunction, so I can keep troubleshooters focused on the more probable causes.