VFD's and the ControlLogix platform

stinklizard

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I sifted through a few old threads on this subject, but most seemed to be troubleshooting specifics. I am sure I could google several sources for information; but does anyone have any recommendations for a start? I don't have a job need or school related task here, nor do I have a specific VFD. I am just very curious and wondered about it before I knew it specifically existed. I do have a 1756-L1, 1756-L55, as well as a ControlNet adapter (1756-CNB/D). Other modules don't seem to be prudent to this, so I've omitted them.

I know some VFDs can take analog input to control speed, and some have specific binary inputs for speed and direction. It would seem an RS232 or ControlNet interface and protocol set should exist.
 
A-B has been making variable speed drives for decades, and integrating them into their PLC based systems.

You can go all the way back to the Bulletin 1336 drive in the late 1980's, which had a RIO (the so-called "blue hose" remote I/O network for the PLC-2/3/5) adapter.

But the integration of drives and PLCs really solidified with the 1336 Plus drive, which had a little CAN-based onboard network called SCANPort to connect to the network adapters and the keypads (called Human Interface Modules "HIM").

Those combined what you would otherwise do with discrete outputs and an analog channel into a digital data block that roughly emulated 1/4 of a logical I/O chassis. You could add more emulated data blocks to transfer more parameters, called "DataLinks".

The approximate layout and functionality carried forward, so that you saw it in the PowerFlex 7-series, and in the PowerFlex 4-series, and now in the PowerFlex 750 series and 500 series drives.

The modern drives grew up with the controllers; there are 32-bit control words and reference values now, instead of 16-bit. And the networks have evolved too; EtherNet/IP is built into many of the drives today.

But the same old Bit 00 = STOP, Bit 01 = START data map will show up in all of those drives.

In ControlLogix, Rockwell started to make drive configuration software an integrated part of the Studio 5000 environment by embedded parts of the DriveTools software so you could click on a drive in the I/O tree and bring up its configuration.

The controllers also started to store more data, so if you replaced a drive you didn't necessarily have to get out the configuration software because all the configuration data was stored in the PLC program itself.

If you want to connect a PowerFlex 70/700 series drive to the ControlNet network you have, you'll need a "20-COMM-C" interface board for the drive.
 
What a great reply. This is a lot of useful information. I will keep my eye out for a powerflex in the more recent releases. Seems like that 20-COMM-C is around $20 on eBay for a working unit, and I already have the controlnet bridge. Thank you so much, this should yield hours of tedious experimentation.
 
+1 for power flex they also support modbus 485 which is another common method of drive comms you, won't be able to use this your controllogix as I believe the local 232 does not have 485, but is good if you want to use the same drive with a plc from other maunfactuers.
 
I am going to use ControlNet or DeviceNet as much as possible. That 20-COMM-C device looks like my answer. The universal nature on the 1756 platform will also be somewhat future-proof for a while; as the market is flooded with only slightly older models at modest pricing. Allen Bradley is still actively producing newer 1756 processors and modules, so I'd say it would be a few years before that backplane is EOL. I can't see the next generation changing too much, so I would assume there would be some backwards compatibility from the next-gen to the current ControlNet; I just wouldn't hold my breath for forward compatibility from the current protocol. They would have a mass riot if the next lineup didn't work with pretty much the industry standard.
 
Integrating Logix to either the PowerFlex 750 or 520 series via Ethernet could not be much easier, and the thing I like most about them is the Automatic Device Configuration you get with Ethernet connections. That means the Logix processor (with a memory card) will store all the drive configurations /programming and if a drive is ever replaced, the processor automatically programs the replacement drive to match what came out. That's a feature that looms large at 3AM on Saturday when the 3rd shift electrician who can't spell VFD wants to call you to reprogram it. Now all he has to know is 3 wires in, 3 wires out and plug in an RJ-45 connector.
 
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I am going to use ControlNet or DeviceNet as much as possible. That 20-COMM-C device looks like my answer. The universal nature on the 1756 platform will also be somewhat future-proof for a while; as the market is flooded with only slightly older models at modest pricing. Allen Bradley is still actively producing newer 1756 processors and modules, so I'd say it would be a few years before that backplane is EOL. I can't see the next generation changing too much, so I would assume there would be some backwards compatibility from the next-gen to the current ControlNet; I just wouldn't hold my breath for forward compatibility from the current protocol. They would have a mass riot if the next lineup didn't work with pretty much the industry standard.

While the Controllogix platform will be around for quite a long time, lots of the hardware becomes quickly outdated, especially the processors. Older models are not able to use the newest firmwares, which mean they cannot use some of the newest software features. Also, the older models are no long manufactured so your PLC programs must be migrated to the newest versions. Luckily, Rockwell has made this migration fairly easy.

As far as controlnet and devicenet, I think they are on their way out. The small advantages that devicenet has over ethernet will disappear as more IOLink devices become available and ethernet is easier, cheaper, more available, and better performing for 99% of tasks than Controlnet.
 
I heard the same thing, that devicenet and controlnet are on the way out. That was 20 years ago. It was only two years ago that I commissioned new systems using Devicenet.
 
I heard the same thing, that devicenet and controlnet are on the way out. That was 20 years ago. It was only two years ago that I commissioned new systems using Devicenet.

General Motors has finally s**tcanned DeviceNet from their spec, and (happily) Ford stayed with RIO before changing their spec to E/IP. If I never see D-Net again I'll be thrilled.
Aside from oil and gas, ControlNet never seemed to really get established. It was pretty solid in my experience, but I certainly would never use it in a new installation...
 
The last D-net job I did was for FCA in Windsor and in italy - right in the middle of Profinet land. From experience, I just don't see it going a way quite yet.
 
+1 for Ethernet/IP

Ethernet/IP, IMO, is the 'universal' Remote I/O protocol. I consider a VFD as an I/O device (in most cases).

Obviously in some cases, the VFD is the 'Master' device and needs to control additional I/O. The problem is, most VFD's can't be Ethernet/IP clients (masters), only servers (slaves)... without a co-processor. So, throw in a PLC to handle the I/O, and hand control over to it. Now the control system cost has multiplied...
 
I am going to use ControlNet or DeviceNet as much as possible. That 20-COMM-C device looks like my answer. The universal nature on the 1756 platform will also be somewhat future-proof for a while; as the market is flooded with only slightly older models at modest pricing. Allen Bradley is still actively producing newer 1756 processors and modules, so I'd say it would be a few years before that backplane is EOL. I can't see the next generation changing too much, so I would assume there would be some backwards compatibility from the next-gen to the current ControlNet; I just wouldn't hold my breath for forward compatibility from the current protocol. They would have a mass riot if the next lineup didn't work with pretty much the industry standard.

I put a hold on ControlNet a couple of years ago. While it is reliable WHEN INSTALLED CORRECTLY, fault finding can be a bear. Same as DNET, or DH+.

Just use Ethernet I/P if you are going with Rockwell, there is seriously zero reason to use any other network.
 
Just use Ethernet I/P if you are going with Rockwell, there is seriously zero reason to use any other network.

+1

We've been Ethernet i/p for almost 4 years now and wouldn't do anything else now. VFDs, PLCs, HMIs, scanners, air compressors, backup gensets, etc. Really is now need to do it any other way on a new installation.
 

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