Controlling a PowerFlex 70.

[tomwhite007_2008]

Processor = Control Logix 5000
Drive= AB PowerFlex 70
Communication = DeviceNet

I am writing a program off-line am not able to test it. My Question is I want to Start a VFD and keep it running. Do I have to maintain "MY_MOTOR.O.Start" high as long as I want the motor running or does it just have to be pulsed to Start it to keep it running? See the Logic below. Will my motor continue to run if I take my finger off the PanelView Push Button "START_PVPB"?

 

[Sliver]

You have the option of controlling the drive with 2 wire or 3 wire control.
2 wire would require a maintained output from the PLC.
3 wire requires a momentary start and a stop input
I believe 3 wire is the default.

Brian.

 

[OkiePC]

With devicenet, you must use a 3 wire mode in which logic command bit 0 is the stop command (set to "1" to stop the drive), and bit 1 is the start command (momentary "1" starts the drive)...

So yes, the drive will continue to run when you release the button, and you need to send a "1" to the stop bit to stop the drive.

Your logic looks correct to me.

Paul

 

[Sliver]

Thanks for clarifying Paul, I have only hardwired these and and do not talk A-B/devicenet. I should read the post more carefully next time.

Brian.

 

[Ken Roach]

OkiePC is right on.

On DeviceNet, the Stop and Start commands are momentary (like three-wire control) but the Stop command is asserted when the Stop bit value is = 1.

I usually program the Stop feature a little differently because of ControlLogix asynchronous I/O exchange and the way SCANport/DPI devices can be configured to "hold last state" in case of communication failure.

Usually, you don't want the Stop command to remain asserted if the drive is disconnected from the network, because it would mean you could not switch to local or manual control and start the drive. I've had that call many times: "the network got broken but now I can't start the drive" because the DNet adapter is still sitting there asserting STOP, just like it's been configured to do.

The other issue is that the RPI for the DNet scanner can expire in between the rungs that determine the Stop and Start commands, so there's the possibility that the Stop and Start bits will both be set = 1 if you program the very common "if not Start, then Stop" rung.

In that case, the Stop bit overrides the start bit, and the symptom is "the drive didn't start when I commanded it to". This is infrequent when you are using things like a PanelView pushbutton, but very common when the drive is starting and stopping every few seconds under PLC program control.

I program the Start bit to stay on only until the drive has started. Likewise, I program the Stop bit to stay on only until the drive is no longer Active.

 

[Gotcho]

Is this the same for other DPI interfaces? i.e. ControlNet, EtherNet/IP

 

[bkottaras]

Is this the same for other DPI interfaces? i.e. ControlNet, EtherNet/IP

True for 22-COMM_E , haven't done it on ControlNET.

 

[bkottaras]

OkiePC is right on.

On DeviceNet, the Stop and Start commands are momentary (like three-wire control) but the Stop command is asserted when the Stop bit value is = 1.

I usually program the Stop feature a little differently because of ControlLogix asynchronous I/O exchange and the way SCANport/DPI devices can be configured to "hold last state" in case of communication failure.

Usually, you don't want the Stop command to remain asserted if the drive is disconnected from the network, because it would mean you could not switch to local or manual control and start the drive. I've had that call many times: "the network got broken but now I can't start the drive" because the DNet adapter is still sitting there asserting STOP, just like it's been configured to do.

The other issue is that the RPI for the DNet scanner can expire in between the rungs that determine the Stop and Start commands, so there's the possibility that the Stop and Start bits will both be set = 1 if you program the very common "if not Start, then Stop" rung.

In that case, the Stop bit overrides the start bit, and the symptom is "the drive didn't start when I commanded it to". This is infrequent when you are using things like a PanelView pushbutton, but very common when the drive is starting and stopping every few seconds under PLC program control.

I program the Start bit to stay on only until the drive has started. Likewise, I program the Stop bit to stay on only until the drive is no longer Active.

OK I'm stealing Ken's setup as of now for the Stop command.
I do like the entire setup.
Thanks Ken

 

[tomwhite007_2008]

Thanks for the answers guys. One more question is the MY_MOTOR.O.LocalControl tag. What roll does this play if it is high? Does it disable network commands to the VFD so you can now use the HIM?

 

[OkiePC]

Local control means that only that port can control the drive command logic (except for the stop command which is always allowed from an active port).

It would be used if there were multiple communications channels being used to control the drive, and you wanted to allow one of them exclusive control of it.

 

[Ken Roach]

SCANPort and DPI interfaces generally work the same with regard to their action during Program Mode and network failure events.

I learned about the simultaneous stop/start effect on a machine that started several PowerFlex 70 drives three times per second. Every couple of days the RPI hit that teensy window between the rungs and one of the drives failed to start.

 

[Ken Roach]

With regard to the "Local Control" bit: I think it would be better named the "exclusive control" bit. Each interface to the drive has a "Local Control" assert feature.

If your terminal block inputs assert "Local Control", then the HIM and the network cannot start or change reference or direction... the terminal block has exclusive control of the drive for all functions except Stop.

Similarly, the HIM can assert Local Control.

Or the DPI interface can assert Local Control.

Local Control can only be taken over while the drive is Stopped.

 

[kamenges]

What, if any, priority exists on the local control bits? For example, if the term strip, the HIM and the PLC all assert local control at the same time, who wins? I assume that going in the first one the drive sees will win. But assume the active local control port removes it's local control bit but the other two sources still have it asserted. Who wins then?

Keith

 

[danghuuphat]

So if installed inverter runs on the keyboard are needed parameters. Your inverter error F48 is reset not to do