Power Flex 40 Devicenet not varying speed

[Freak]

Hi - I have done some searching and answered a lot of my questions but.....
I have a Powerflex 40 drive communicating to an 1769-L35 over devicenet. I am able to start and stop the drive no problems but the speed isn't varying at all, it is either 100% or 0.
I have checked and the word I am sending to the drive is changing for speed (second half of DINT).

I am sure I am missing something simple but I can't find it.

 

[beethoven_ii]

The output data to the drive is usually 2 integers, the 1st one being the control word and the 2nd one being the speed reference. A value of 500 in your speed reference word should make the drive run at 50.0Hz

 

[beethoven_ii]

The other thing to consider is whether you have set the drive to get it's speed reference from comm port in parameter 38.

 

[jraef]

The other thing to consider is whether you have set the drive to get it's speed reference from comm port in parameter 38.

Yes, that's the first thing that came to my mind. It's not enough to tell the drive that the Run command will come from the communication port, you also must tell it how it will get its speed reference. So if you did not set that to be the comm card, the drive speed will go to whatever reference it is looking for and if that is left to the default of "Keypad" and the keypad reference is 100%, then when you command it to run, it runs at 100%.

 

[jdbrandt]

The other thing to consider is whether you have set the drive to get it's speed reference from comm port in parameter 38.

I agree, but also remember to look at MAX Frequency and MIN Frequency parameters, since they might be masking the real problem, whatever it is. P038 would be my first goto on a symptom like this...

 

[osmanmom]

other reference,


https://rockwellautomation.custhelp.com/ci/fattach/get/89809/

 

[Freak]

P038 is set to comms port.
Attached is PLC program and Devicenet configuration. In the PLC it is under Wine_Pump/S03_Devicenet.

The Devicenet file is just S2_Tankfarm.doc (change extension)
The PLC is the other one with the date, also change the externsion.

Cheers

 

[Freak]

Problem fixed. I re-cehcked the manual after as nights sleep an a couple of cups of coffee (turns out the scotch I was drinking last night (at home) while working on this didn't help???)

The issue was that I wasn't turning on bits 12 and 13 in the command word to tell it to use the comm frequency.


Cheers

 

[jraef]

Note to self: Scotch + PLC code problem solving = Fail.

Got it... thanks for the tip!

But the important question is, what kind of Scotch? I'm partial to Glenlivet single malt.

 

[Freak]

It was the 12 year old Glenlivet - straight up

I'm also partial to Chivas... and Jamesons for an Irish twist

 

[kamenges]

Originally posted by jraef:

Note to self: Scotch + PLC code problem solving = Fail.

Not necessarily. Sometimes it will turn the gain down just enough to get you out of oscillation so you can settle on the setpoint.

I'm not much of a Scotch guy so I can't help you there.

Keith