Trending Powerflex 700 Parameters

[computerwolf]

Hi. I'd like to know if it's possible to trend the DC Bus parameter of a Powerflex 700, series B. I can see the start/stop, etc. parameters in the RSLogix 5000 program (via a 1756-CNB ControlNet module), but I'm not seeing anything resembling the DC Bus parameter.

The reason I'm asking is that recently we've been having an Overvoltage fault on the drive. We were seeing a high bus voltage (760V-780V) on this drive, even after lowering the incoming voltage, (which helped some). The motor being driven is constantly changing speed (average 44fpm) to maintain tension on the sheet and we suspected regeneration. We installed braking resistors, but that didn't seem to help. The other night we were browsing through the parameters and found one called "Regen Power Lmt", or something to that effect (Param 153, I think). The manual explained that this is the amount of regenerative power to be sent to the DC Bus, and that if we had a braking resistor, it was supposed to be set at maximum (_50 to 0%). It was set to the factory default of -50%, and we changed it to 0%. The minute we did, the DC Bus voltage dropped to 650V, which is where it's supposed to be. So now, we'd like to have the capability to trend the DC Bus parameter for future reference.

Any possibility this can be done? If you need more info, it might have to wait until I get to work tonight. Thanks for any help,

John Wolfe
Corinth, Texas

 

[controlsdude]

if the drive is on devicenet than it would be very easy to bring this info back to the plc to datalog. Otherwise you could use an analog out and data log it on a pen graph.

 

[andybro]

In order to access parameters over and above the default ones available on Controlnet (or Devicenet/EthernetIP) you can set up Data Links in the Powerflex drive and map the required parameter into one of these. You will also need to update the Drive setup in Logix 5000 so that the expected input and output data sizes are increased to accomodate the Data Links. All of the required information is in the Rockwell manuals and it is actually much easier than it sounds.
Andybr

 

[jde777]

Parameters 13, 35, and 26 will need to be changed when the datalinks are enabled.

page 84

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/20comm-um003_-en-p.pdf

 

[GHaulk]

If I'm not mistaken, the latest version of Logix 5000 has Drive Executive included in it. If you don't have it, I would look at investing in it. It is a very handy tool when trying to monitor and trend drive parameters. Hope this helps.