Messaging across VLANs on a Stratix switch

mylespetro

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Dec 2015
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Hey everyone,


First project working with a managed switch, chose to use it due to having a DLR network with 8 drives. Local PLC (let's call it PLC2) with the drives is on VLAN 100, so the PLC is 192.168.100.1, drives also have IP addresses in this range (192.168.100.11 thru 19, skipped .16 and .17 for future drives to be installed later). Want to send data from this PLC to a remote PLC (PLC1) on VLAN 5, IP address is 10.20.5.3. PLC1 is on port 1, with port 3 also being on VLAN 5, while PLC2 is on port 2 with port 4 also being on VLAN 100, and the drive DLR is connected on ports 7 and 8, also on VLAN 100.


I believe we have a good link between PLC1 and the switch over fiber as evidenced by the Tx/Rx lights on our fiber-copper converters, currently getting a slower flash because we haven't actually begun transmitting data yet. When I changed my laptop's IP address to be on VLAN 5 and plugged it into port 3 the Tx/Rx lights started blinking much more rapidly, I assume because there was actually traffic on the link.


The PLC2/DLR connection is also up and running well, so now the goal is to read data from PLC2 using MSG instructions in PLC1. My main question is how to cross the VLAN on the Stratix switch? Not sure if I'm overthinking it or not, or if I have to do some configuration in the switch itself. I have enabled Lanbase Routing, just not sure what else has to be done.



Attached is a screenshot of the system layout, note that all of the highlighted IP addresses have been changed to have 192.168.100.X instead of 1.X, as well as the top two ports on the Stratix 5700 being reversed. The ControlLogix is PLC1 and CompactLogix is PLC2.


Thanks in advance!


EDIT: Just wanted to add that there are existing MSG instructions in PLC1 that used to gather data from an old SLC over DH+ that we upgraded with the CompactLogix, so I'll just need to change the MSG types to CIP, element syntax and message path, essentially just looking for how to path from VLAN 5 to VLAN 100.

Stratix.jpg
 
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Hello mylespetro:
Please clarify. The remote PLC in DPU room's EtherNet/IP modle has IP address 10.20.5.3 and you want this PLC to communicate with the PLC in the coal feeder panel whose IP address is PLC is 192.168.100.1? This is not possible because these PLCs use EtherNet/IP and thus they communicate through IP or Internet protocol. The VLAN would help Ethernet nodes connected to the STRATIX switch on the DPU room connected to network 10.20.XXX.XXX not getting traffic from the Ethernet IP side which could contain multicast traffic that you would not want to go to other ports in the switch other than the port to which the PLC is connected, but both PLC must be configured within the same IP subnet. If the PLC in the DPU panel is communicating with things like SCADA, or human machine interfaces or SQL databses which belong to the 10.20.XXX.XXX subnet, I am afraid you will need an additional EtherNet/IP module, or you will have to use a different IP setting for the nodes in the coal feeder cabinet panel.
 
Hello mylespetro:
Please clarify. The remote PLC in DPU room's EtherNet/IP modle has IP address 10.20.5.3 and you want this PLC to communicate with the PLC in the coal feeder panel whose IP address is PLC is 192.168.100.1? This is not possible because these PLCs use EtherNet/IP and thus they communicate through IP or Internet protocol. The VLAN would help Ethernet nodes connected to the STRATIX switch on the DPU room connected to network 10.20.XXX.XXX not getting traffic from the Ethernet IP side which could contain multicast traffic that you would not want to go to other ports in the switch other than the port to which the PLC is connected, but both PLC must be configured within the same IP subnet. If the PLC in the DPU panel is communicating with things like SCADA, or human machine interfaces or SQL databses which belong to the 10.20.XXX.XXX subnet, I am afraid you will need an additional EtherNet/IP module, or you will have to use a different IP setting for the nodes in the coal feeder cabinet panel.

Alright, I was under the assumption that my local AB PLC/networking rep said that I would be able to send a message across the VLANs, but I was having trouble seeing how that would be possible. It would be easier just to put the CompactLogix on VLAN 5, which is actually fine by me, as all of the distributed plant PLCs are also in this IP address range, but I would have preferred not to have the drives eat up 8 IP addresses on that network. It is the easiest option to get the system up and talking though, so that’s probably what I’ll do.

Thanks for the reply!
 
I emailed the AB rep and he said that the full software version of the Stratix 5700 will allow lanbase routing, and therefore will allow routing across the VLANs. I’m fairly certain we have the full software version, as I’m able to turn on the lanbase routing SDM template, so it looks like I’ll have to configure the routing path.
 
...I would have preferred not to have the drives eat up 8 IP addresses on that network.


Change the network mask to 255.255.254.0 on 192.168.100.0 and it will roughly double the address space on that LAN*.


* 192.168.100.0 to 192.168.101.254; 192.168.101.255 is the broadcast address; this assumes it does not have, or need to route to, 192.168.101.0/255.255.255.0.
 
Beware, the information below is assuming that neither of your PLCs are already communicating with a different subnet through a different router.
If either of them are, doing this will break that communication.

It sounds like you have a switch that is capable of routing and it sounds like you have it enabled correctly. Now you just need to give your switch an IP address on both of your subnets and use the switch IP addresses as the default gateways of your respective subnets.

You didn't say what your subnet masks were, but assuming you are using the very common 255.255.255.0, you could for example, set your switch VLAN 5 interface to 10.20.5.254 and switch VLAN 100 interface to 192.168.100.254. Then your 192.168.100.1 PLC would get a gateway address of 192.168.100.254 and your 10.20.5.3 PLC would get a gateway address of 10.20.5.254.
 
Thanks for all the info guys, I’m not exactly familiar with networking more advanced than the very basics, so this has been a bit of a learning experience for me.

I’ve made a bit of a change of plans, I now have PLC2 on the same network as PLC1 (I EDIT:gave PLC2 an IP address of 10.20.5.30), and would like to keep the drives on the DLR on the 192.168.100.X VLAN, so now I would be looking to do the routing between the DLR and PLC2 instead of between PLC2 and PLC1. I looked up a couple articles and videos on how to configure routing on the Stratix 5700, but they seem pretty vague to me, and when I tried to follow one video’s instructions on enabling routing with the gateway entered as 0.0.0.0 in order to “route all traffic from any VLAN” (to quote the video), it gave me an error saying that it was an invalid address. I looked that up and it said that you have to do that before configuring the VLANs so I may need to reset the switch to factory settings and start over.
 
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Hey everyone, got it working. Put PLC2 back on the same VLAN as the drives and enabled routing with no gateway. I was able to ping all networks from my computer regardless of what VLAN I was on, so then I had to add my Stratix IP as the gateway on the EN2T of PLC1 and then configure my message path as “1, 6, 2, 192.168.100.5 (new PLC2 IP)”. I had thought that I would need to add “1, 0” to the end of the message path, but not for the CompactLogix. Turned out to be much easier than I anticipated, the only hiccup was I had to add the gateway IP to the parameters of the network card on the drives to get them to show up in the IO tree of PLC2.

Thanks to everyone who chimed in!
 
Cool. Ethernet/IP path is always difficult for me too. I have to dig out the info everytime I set up one.

Regarding "private IP". Yes, it can be routed, just not on the internet where routers automatically disregard it that's why your "internet service router(modem)" does NAT. A lot of hard core user have router in their basement and there are a lot of videos on youtube on home routers (not internet service router).
 

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