PowerFlex 70 400 VAC ( 20AC022 ) vs PowerFlex 70 480 VAC and Devicenet Mismatch

Good Evening ,

We have 4 machines that were manufactured in the UK . They came over with PowerFlex 70 400 VAC Drives on them ( 20AC022 ). Our maintenance technicians say that we need to always send the bad drives out to get repaired because , the PowerFlex 70 480 VAC Drives ( 20AD022 ) will not work on DeviceNet . I imagine because of a mismatch , because of the different part numbers , possibly ? If so , what parameters would need to be changed to accept the different drive ? None of us are familiar with DeviceNet . What have you folks done before to deal with mismatches , if this is the case ?

Thanks so much for your help ,

This might be as simple as a change to the Electronic Keying elements in the Scanlist entry for the drives.

Electronic Keying exists to add a degree of consistency to the network, so that you can't accidentally run the wrong device just because you misconfigured the address and I/O data size the same.

So each Scanlist entry allows you to configure the Scanner to check different elements of the slave device's Identity object: the Vendor number, the Device Type, the Device Code, and the Major and Minor firmware revisions.

A 400V drive and a 480V drive will have different Device Codes, but the same Vendor (A-B) and the same Device Type (DPI interface drive).

There are two ways to resolve the device mismatch if you replace a 400V drive with a 480V drive.

The first is to simply disable Electronic Keying. Go to the Scanner's scanlist table, and un-check the Electronic Keying box for the Device Code. Save the Scanlist, and you're done.

The second is to do a "resolve device mismatch" in which the Scanlist keying codes are modified, so the Scanlist contains a 480V drive. This is offered in RSNetworx for DeviceNet software as a right-click option when you scan a network and the software finds a different device on the network (the 480V drive) than exists in the Scanlist (the 400V drive).

To do either one of these changes, you will need RSNetworx for DeviceNet software and a way to connect to the network.

What model of controller and DeviceNet network interface card do you have ?

Two other things to mention:

If you aren't familiar with RSNetworx and don't have a backup file for the network configuration, be *very* careful with the difference between "uploading" data from the devices, and "downloading" data from the software to the devices.

You can thoroughly screw up a DeviceNet system by going online with a fresh session of RSNetworx, "browsing" so that the devices are seen in the network view, then commanding a "download to network". That causes all the default settings from the EDS files (remember, the network project file doesn't know any of the settings in the actual devices yet) to be downloaded.

Also, it's possible that your OEM set up the system to use "auto device replacement", in which all of the parameters for the drive are stored both in the drive and in the DeviceNet scanner module.

This is useful on systems where devices fail or are damaged often: the Scanner simply identifies that you've put a new device into the machine (because the checksum doesn't match) and loads all of its configuration parameters automatically.

I don't recommend it for AC drives, for a couple of reasons.

One is that it takes up a lot of memory and time; a drive has hundreds of parameters.

Another is that it introduces the risk that you'll make a tuning or adjustment to a drive and forget that the scanner still holds the old parameter value. All is well.. .until the system undergoes a power cycle and the scanner over-writes your adjusted value with the saved value because the checksums didn't match.

You can see in the DeviceNet Scanner module configuration whether or not "ADR" is configured for the drives. Hopefully it's not.

Best thing to do for your drives is to go online with the network and upload all their parameters using RSNetworx for DeviceNet. Then you'll have a baseline to work with and a set of parameters to use in case of a disaster.


I always say DeviceNet is a lot like swimming: if you learn the basics and proceed carefully, it's a lot of fun. If you just jump in without looking, you're going to have a bad time.

Thanks Mr. Roach ,

This is a SLC 500 5/05 CPU . Can I see and modify the scan list thru Ethernet ? Also , I looked up the scanner module and under the scanlist tab ,
I see in the Electronic Key that all of these are checked......

Device Type
Vendor
Product Code

Which one should I uncheck , Device Type ? And I need to use RS Networx / DeviceNet , correct ?

Thanks,