Isolation of an Ethernet PowerLink network

[Ken Roach]

I have inherited a system that uses a Parker ACR9000 motion controller with the Ethernet PowerLink option that it uses to control five Parker Compax3 servo drives.

Each device has a two-port Ethernet Powerlink option board. Today, they are set up in a simple Port 2- > Port 1 "daisy chain".

The ACR9000 has a separate Ethernet port that it uses to talk to ACR-View 6 software as well as a custom Windows application. That separate Ethernet port is connected to an ordinary unmanaged switch.

According to my research, the Compax3 can actually communicate over both Ethernet PowerLink and TCP/IP via that same EPL port on TCP ports 44821 and 44822, in addition to via RS-232 and RS-485 on its serial port.

I don't have any experience with Ethernet PowerLink. I've read that it's fast and easy and basically CANOpen over Ethernet. I've read that you can use ordinary Ethernet switches with it.

But what I don't know is if it uses Ethernet frames that are going to get propagated to the rest of my network if I go ahead and plug that Ethernet PowerLink daisy-chain into my unmanaged switches. Every diagram I've seen about it either restricts itself to the realtime domain or hand-waves about separating realtime domains from one another with "gateways".

So the question is: if I plug this Ethernet PowerLink network into my unmanaged switch, am I going to choke the normal Ethernet TCP/IP computers and PLCs with Ethernet PowerLink frames ?

If so, what really is a "gateway" that I can install so that I can have TCP/IP access to that Ethernet PowerLink network without passing all the realtime traffic onto a LAN ? Do I just need a switch with VLAN routing ? Does Ethernet PowerLink even respect VLAN tags ?

 

[robertmee]

I've used Hischler gateways for older Parker servos, but it's been years. Anybus makes one.

Ethernet Powerlink | Anybus 2023

Ethernet Powerlink, connect Anybus gateways to all major fieldbus and Industrial Ethernet networks. Integrated Powerlink connectivity through Anybus CompactCom.

www.anybus.com

 

[chelton]

From what i've seen of B&R Powerlink. All powerlink devices are on the 192.168.100.xx network. With the unit number on the device being the host number in the IP address. Powerlink is a broadcast protocol, so i would keep it off your normal network. I would think putting a NAT router and just using 1:1 mappings to get tcp/ip access to the specific devices would keep the broadcast traffic isolated.

 

[chelton]

Ken, here's a link to the powerlink specification Ethernet Powerlink

 

[Ken Roach]

Thanks, guys ! The specifications and white papers and so forth give me flashbacks to trying to sound smart about Ethernet when were all accustomed to DH+ and Modbus Plus.

What I'm concerned about is having raw Ethernet frames on my switch, not just for it's own switching speed but also because I don't want the customer PC or my HMI to have to deal with a bunch of raw Ethernet that's not even carrying TCP/IP for its port. I'm not sure if your average PLC or HMI device can handle being on a PowerLink network, and it seems like the folks writing specifications and whitepapers aren't willing to come out and say "don't connect anything else to the EPL" or say "here's the sort of device that can filter out EPL easily and leave its Ethernet NIC free to handle ordinary TCP/IP".

I think my approach to this particular challenge is going to be to install a Red Lion DA50D. It has two separate, isolated, and independent Ethernet ports, so I can connect one to the same network as the customer PC and the ACR9000's programming port, and the other to the EPL network that contains the Compax3's.

For testing I'm going to use a Red Lion DSPSX that I have in the lab, and my PC's ordinary NIC, and just plug those into the daisy-chain of the EPL network. I guess we'll see how they do.

 

[Ken Roach]

And thanks for that confirmation that typically an EPL network also carries TCP/IP on the 192.168.100.x subnet, where the host number = the PowerLink node. That's another reason I need some kind of router or bridge or NAT in between these networks, because my enterprise connection uses 192.168.10.x and the addresses are (sigh) hard-coded into compiled executables.