PowerFlex 700: Motor doesn't stop on Comm Fault.

[DPorragas]

Good evening; im working with a PowerFlex700 and i need to e-stop the drive in case of a Communication Failure.

• The PF700 is connected to a DeviceNet Linking Device bridging to a ControlNet.
• 20-COMM parameter #20 Cmm Flt Mode = 1 'Stop'.
• PF700 parameter #155 Stop Brk Mde A = 1 'Ramp'.

With motor running:​

1. When i use the stop command (via local or via RsLogix Tag) the motor stops with decel. ramp.​
2. When i disconnect the DeviceNet the motor stops the same.​
3. But when i disconnect the ControlNet the motor stops by means of inertia only.​

Why is this difference?

The actual problem was that we had a brief ControlNet communication failure (maybe noise, whe don't know exactly) and the motor was supposed to stop but when the fault ocurred the motor didn't stop until they pressed de emergency stop.


We actually have a similar off-the-line system (PF700 and a motor), i am trying to simulate the same error.​

​

Thank for your comments and help.​

 

[Ken Roach]

When the 1788-CN2DN detects a break of the connection across ControlNet, it places all the slave devices into an Idle mode. To the PowerFlex drive, this is the same as the logic controller being placed into Program mode.

There are two communication state related parameters in the 20-COMM-D interface:

[10] Comm Fault Action
[11] Idle Fault Action

The parameter values for both parameters are the same:

0 = Fault
1 = Stop
2 = Zero Data
3 = Hold Last State
4 = Send Fault Config Value

 

[DPorragas]

Thank you very much. It helped me a lot.
In wich manual can i found information related?

So, back in my physical problem, the motor didn't stop because of the inertia of the load or...

Could it be that after the brief failure the system reset itself, went back to normal operation and started the motor again missing some limit switches, for example?

Again, thanks Ken. I'm still trying to figure out what the problem was, i'm going to analyze the info in the DriveExecutive file of the failed PF700.

I'll keep you informed.

 

[DPorragas]

I'm testing right now, and i see that with:

[10] Comm Fault Action = STOP
[11] Idle Fault Action = STOP

If i provoque the fault (by means of DN or CN), the motor stops but the HIM shows no fault.

I guess i'll have to do logic control if i want to stop and show the fault.

The real question is; if i set

[10] Comm Fault Action = FAULT
[11] Idle Fault Action = FAULT

and then add logics to stop on device fault, how can the PowerFlex or Linking Device 'hear me' if the communication was lost?

 

[Ken Roach]

When you select "Fault" as parameter value, the drive detects an Idle or Comm Fault condition and stops and displays a DPI serial fault code, usually fault code 75 when the 20-COMM-D is mounted in its usual internal location.

This fault can be cleared using the STOP button on the HIM, a discrete input (usually the Stop/Clear Faults input) or over the network once communication is restored.