SLC 5/05 Ethernet

I have Allen-Bradley 753 VFDs that I would like to control through ethernet. I have a SLC 5/05. I am currently communicating through the ethernet port to a prosoft ANX module switching to DH+ in order to send messages to a PLC5. I would like to know if the 5/05 is capable of putting a switch in and also communicate with my vfds. I know that you can't communicate with the 1794-aent flex IO module through that ethernet port, so Im curious if I would be able to communicate with the drives. Any advice?

A-B variable frequency drives happen to have a PLC data table emulation mode that allows them to be controlled using unscheduled messages from a controller that cannot otherwise control I/O devices on Ethernet.

This is my attitude toward that control method: http://www.youtube.com/watch?v=UU_GhqVgc9M

mwftech said:

I have Allen-Bradley 753 VFDs that I would like to control through ethernet. I have a SLC 5/05. I am currently communicating through the ethernet port to a prosoft ANX module switching to DH+ in order to send messages to a PLC5. I would like to know if the 5/05 is capable of putting a switch in and also communicate with my vfds. I know that you can't communicate with the 1794-aent flex IO module through that ethernet port, so Im curious if I would be able to communicate with the drives. Any advice?

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In short, maybe but don't. The ethernet port on a 5/05 was never intended to be used for controlling I/O or Drives. It is not the same type of IP used in the logix platforms (which is why a 1794-aent will not work with the 5/05). If you are curious as to the Why's of that I am sure someone here will explain determism and fail safety better than I could.

Your options for controlling drives that I know with a SLC of are Devicenet, Controlnet, or RIO.

Edit: Ken beat me to it and is the man when it comes to this kind of stuff with AB controllers.

Thank you for the replys. So there is no other way to get a SLC connected to ethernet for data transfer? If someone knows of a link that has good learning materials on the slc ethernet capabilities I would appreciate it.

ken roach said:

a-b variable frequency drives happen to have a plc data table emulation mode that allows them to be controlled using unscheduled messages from a controller that cannot otherwise control i/o devices on ethernet.

This is my attitude toward that control method: http://www.youtube.com/watch?v=uu_ghqvgc9m

Click to expand...

HA Very good.

The 5/05 ethernet channel works fine for passing data to and from HMI's, for programming, and communication between processors. It was just not designed for controlling I/O. I haven't watched Ken's video but the main reason you don't want the 5/05 controlling I/O is determism.

Basically with regular TCP/IP when a packet or message is sent out of the controller there is really no inherent mechanism to guarantee that it has reached the intended target and no way to determine how long it will take to get there. If the packet colides on its way to the drive the controller will simply send it again, and again, and again... So if you were sending a stop or a ramp down signal to your drive and that message doesn't get there (packet storm or whatever), then your drive might not stop. Obviously this could lead to a very bad day.

The logix family schedules data transfer so that every xxxmS there is a guarantee that the messages will be sent or received and if not the controller and I/O take appropriate actions.

This is a lay mans explanation because that is what I am. I was hoping someone here would explain it better or link to an article that can explain it better than I can.

allscott that explained it very well, thank you. I reviewed the manual and what I am getting out of it is that the 5/05 ethernet port is mainly meant for sending and recieving message instructions from other processors such as PLC 5 or another 5/05. I appreciate the help. I am not familiar enough with controlnet or devicenet to go that route so I may just do it old school and use analog modules for controlling my drives.

I have done these drives over Devicenet. There is a lot of functions that can be done that way but it gets deep, real fast. You have to learn about Datalinks, realize which datalink sends what to the PLC and which datalink sends what to the 753. There are about 1673 parameters if I remember correctly and the manual is rough. Good luck with your adventure, I hope it turns out better than mine did.

Thanks for the advice. Is controlnet just as difficult?

Don't get me wrong, if you have time to do the Devicenet and figure it out it is very useful. I was under a lot of pressure and very very little time to do it so it was miserable. I have not worked with Controlnet other than the 1788-CN2DN card so I can't answer that.

ControlNet on an SLC platform is a bit dicier then DeviceNet.
I really think you should consider using DeviceNet for controlling the PF VFDs.
For basic operation (Start/Stop, Fwd/Rev, Jog and digital speed reference) you cannot beat DeviceNet especially on legacy platforms.

I will have to check with my bosses how much time they want to allow me on this project. I want to learn it so I have it as a resource but it may be something I tackle over time. If any of you have found a good manual or learning platform/link I would appreciate it. Thanks for all the info thus far.

http://literature.rockwellautomation.com/idc/groups/literature/documents/um/dnet-um072_-en-p.pdf
http://literature.rockwellautomation.com/idc/groups/literature/documents/in/1747-in058_-en-p.pdf
http://literature.rockwellautomation.com/idc/groups/literature/documents/um/1747-um655_-en-p.pdf
http://literature.rockwellautomation.com/idc/groups/literature/documents/um/20comm-um002_-en-p.pdf
http://literature.rockwellautomation.com/idc/groups/literature/documents/gr/dnet-gr001_-en-e.pdf
http://literature.rockwellautomation.com/idc/groups/literature/documents/pp/1784-pp016_-en-p.pdf
http://literature.rockwellautomation.com/idc/groups/literature/documents/in/1784-in046_-en-p.pdf

While I would agree devicenet would be the way to go RIO may also be an option. It is easier to wire and set up than Devicenet IMO. If you already have an RIO scanner in the slc it is less costly as well and does not require RSnetworks to configure.

I said may because I am not familiar with that particular drive so I don't know if that is an option or not.

I am somewhat partial to old school analog control on simple systems for a couple of reasons. A technician can troubleshoot systems with a meter rather than having to go online with a processor. Secondly if your AB drive blows up and and you need a replacement NOW and don't have a replacement one with whatever bus you are using, you may be able to install somebody elses drive in a pinch, every drive has analog...

But I am old school and this line of thinking is slowly being replaced. Any new systems that I install with more than a couple drives or if anything complicated is being done I use a bus.

I am somewhat partial to old school analog control on simple systems for a couple of reasons. A technician can troubleshoot systems with a meter rather than having to go online with a processor. Secondly if your AB drive blows up and and you need a replacement NOW and don't have a replacement one with whatever bus you are using, you may be able to install somebody elses drive in a pinch, every drive has analog...

Click to expand...

Bingo, save yourself the grieve and hardwire it. How many wires can it take to start/stop and set its speed?