Working on a Project with Powerflex 525-How can you increase the Max. Freq by the PLC

Good Afternoon ,

I'm working on a project with a CompactLogix and PowerFlex 525's . I plan on having a HMI screen that will allow some changes to the diameter of a pulley , Output of a gearbox , and I would like to change the maximum freqency of the drive from the PLC so that I can expand it's range. What is the best way I can do that ? I took notice that the drive did not populate any controller tags associated with Min. / Max. of Frequency . I know when I set up the drives I was able to setup some input data , such as the Output Freq. , Output Current , Fault Code , and DC Bus Voltage . On the right hand side there are some possibilities for Outputs. Could I write to the Max Freq. there ?

Thanks so much,

You can add a datalink, see photo from a project I did before. You can also message to the drive. Sometimes this might be better since this parameter is usually not changed very often.

Edit, I read your question backwards. Oops, so, if you want to write, I guess message is your best bet. You probably still need to read it though if you want to verify.

Sorry for my dumbness , but what would be the best way to write to Parameter P044 , from the PLC . I looked in the dropdown with your
example , and did not see the Max. Freq.

Thanks for your help.

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/520com-um001_-en-e.pdf
The embedded Ethernet manual explains the messaging. If you do this, be careful to do a one time write only as needed. The flash memory has limited writes (hundreds or thousands but not unlimited). Consider setting the drive for the maximum speed and changing the output scaling in the PLC program.

Cydog said:

Sorry for my dumbness , but what would be the best way to write to Parameter P044 , from the PLC . I looked in the dropdown with your
example , and did not see the Max. Freq.

Thanks for your help.

Click to expand...

Yeah, I didn't read your question right. I guess it's not an option in data links. You can message.

Why do you want to change the actual max freq?

Why not set a max freq and adjust speed?

So after reading your question again, I think you would be better off just changing the speed setpoint not the actual max frequency.

In the drive find the Parmenter for the Max Freq. and set it to what you want.
I would recommend that you start 90Hz above that you may run in to problems.
But keep in mind that as you increase the freq. above base speed the motor will go into constant torque mode of operation and you may not have enough torque to handle the load.
If you are using an analog input to the drive to control speed the when you increase the max freq you also increase the range of the analog signal to drive
10v = 60hz will now be 10v = 90hz he drive should handle the reset for you.

Yea. I see what you mean.

Phrog30 said:

Yeah, I didn't read your question right. I guess it's not an option in data links. You can message.

Click to expand...

I *think* that the only available parameters for output datalinks are parameters that can be changed while the motor is running. Which makes sense, really.



Max frequency can't be changed while the motor is running, so you can't use it as a datalink.


I'd agree with the others that have said, just set your min/max frequency to the lowest/highest possible values, and have your PLC directly control and limit the speed over ethernet. That's how I do it.