Powerflex 4 to/from AB 1746-OW16 Relay Module

[computerwolf]

I have an AB relay module (1746-OW16) controlling a PowerFlex 4 drive, that in turn is powering a conveyor. There are actually many conveyors at my plant that have the same configuration.

The PF4 is configured for 2-wire control, with terminal 1 being being the Stop command and jumpered to terminal 11 (+24V), and terminal 2 being the Start command. The drive is also configured as the "Source". Based on my extremely limited knowledge of "Source" and "Sink", it's my understanding that the "source" provides the voltage/current and the "sink" receives it.

If that's the case, how in the world is the PLC output relay card "telling" the drive to start? I tried measuring voltage, both DC and AC and get nothing on AC. On DC, I get +5V whether the conveyor's running or not.

But the kicker is that when I measured it the following day, I got 35vdc!

More info: The cable connecting the Drive with the PLC is 2-wire shielded and the Start signal runs through an e-stop relay before being terminated at OUT2, while the stop signal runs through an MCR that's connected to a terminal on the module called V1.

I really feel like I'm missing something here. I can usually figure these things out, but this one's kicking my rear.

Any help would be greatly appeciated.

John
Sherman, TX

 

[jimfun71]

FIrst the label of stop is really misleading it's more like a run enable bit. This is where I normally put all my safety stuff. This must be powered to enable the drive to run. The run command is where I put my conveyor logic like photoeyes and such. The drive emmits 24vdc from I think pin 9 "PLEASE DON'T QUOTE ME AS I DONT HAVE A BOOK HANDY." and then you send it to pins 2 for run enable and 3 for run foward.
The relay card on the plc only takes the voltage you give it and sends it out on the output number you designate on the plc card.
To proprely measure the voltage make sure you measure from the drive 24vdc out to the 24vdc common. You must ysu the common from where the voltage orriginated.

 

[bernie_carlton]

1. E-Stop - kill all power to the drive. If it is safer to allow the drive to bring motion to a stop then break the drive terminals 11-2 path and let the motion stop THEN kill all power to the drive.

2. Run - make a connection from drive terminal 11 to drive terminal 2 using the PLC module. Removing the 11-2 path should command a stop at the drive's decell rate.

For the discussion drive terminal 11 is the drive's source of 24VDC. Terminal 1 is more properly named a 'Not Stop'. Depending on drive mode terminal 2 can be a general 'Run' or a 'Run Fwd' if directional control is to be used.

 

[brucechase]

I never kill all power to the drive. I use a safety contactor in the output of the drive. I run the enable command through the safety contactor and drop the drive output and kill the run at the same time.

As for control, I have dozens of conveyors being controlled by VFDs. I use 2 wire control and have AC outputs. I use a relay contact closure between 2 and 11 for running so your contact closure should be the same. For voltage measurements, the 24 Common on the drive is terminal 4.

 

[computerwolf]

Thanks for the replies everyone. So if I understand this correctly, the PF4 is the source of the 24vdc via terminal 11. The common for this 24v is terminal 4.

The 24vdc to terminal 1 is more or less considered a "Run Enable" signal and should be continuously present provided the drive isn't shut down completely.

That same 24v is sent to the PLC relay module. The relay module will send that voltage to terminal 2 of the drive based on the PLC program...in my case, photoeye inputs.

24vdc arrives at terminal 2 of the drive and turns on the motor.

So I should be able to measure that same 24v, the common being terminal 4 of the drive, at either terminal 1 (constantly) or terminal 2 (depending on the state of the relay module).

Thanks again for your help, I do appreciate it.