AB 1756-L7x Redundancy and 1734-AENT are in different VLAN, multicast will work?

[Kanna006]

Hi to All, I have a 1756-L7x redundant processor in one VLAN gateway is 10.17.120.1 and 1734-AENT in another VLAN gateway is 10.17.130.1, subnet mask is same as 255.255.255.0 for both VLAN. And the both the VLAN IGMP with query enabled, multicast port opened. But, am getting this error in studio 5000 V30.01. "Module Fault (Code 16#0813) Multicast Connection requested between a producer and consumer that are on different subnets. Only unicast connections are supported across multiple subnets".
When we select Unicast option in 1734-AENT, Redundancy fails. You guys, facing this kind of issue anywhere, welcoming suggestions & solutions.

Thanks in advance,
Kannan N

 

[mk42]

Don't know much about redundant Logix, only looking at this from a networking perspective:

Is there some kind of router between them? What kind?

Those two IP/subnet pairs definitely can't talk to each other without help.

 

[shawn_75]

Inter VLAN routing needs to be setup on your switch to allow the unicast traffic between those VLANS. Looks like Studio recognizes the mismatch and won't let you use multicast this way, even though you'd be able to setup a switch to accomplish this. Because you are being blocked by the Rockwell software (rather than it just not working), I'd get unicast setup to work. If you're using a Cisco switch and Cisco Network Assistant, InterVLAN routing is fairly straightforward to setup.

 

[Contr_Conn]

Redundancy can only do multicast I/O - no unicast.
Same for consumed tags - multicast only.
Multicast is not routable by definition (TTL=1).
You must have I/O on the same VLAN, or add non-redundant controller on the same VLAN as redundancy to control I/O using unicast.

 

[Kanna006]

1756-L7x in VLAN and 1734-AENT in another VLAN data reading through class-3 message

Hi,
Understood, redundancy and RIOs will not work on different VLANs. Here, I have found solution for the problem by using class-3 message instruction to read DI, AI data and write DO data.
1. Add the modules in I/O tree of different VLAN RIO from PLC and Inhabit.
2. create message instruction in logic, for DI data read
i. Message Type : CIP Generic
ii. Service Type : Get Attribute Single
iii. Service Code : E
iv. Class : 0x08
v. Instance : 1 for Channel – 0 and 2 for Channel – 1….8 for Channel – 7
At a time one channel can be read, logic developed for generating
instance 1 to 8, the instance has moved to Message Instance (data
type is DINT).
vi. Attribute : 3
vii. Destination element : SINT or INT data type tag
viii. Path: Array of string data tag created in logic, the same has copied to
message instruction by passing the slot number of the module.
ix. Received D/I data will be available on 0th bit of Destination element,
the same moved to another SINT data type tag by using BTD.
3. For DO data write,
i. Message Type : CIP Generic
ii. Service Type : Get Attribute Single
iii. Service Code : 10
iv. Class : 0x09
v. Instance : 1 for Channel – 0 and 2 for Channel – 1….8 for Channel – 7
At a time one channel can be Write, logic developed for generating
instance 1 to 8, the instance has moved to Message Instance (data
type is DINT).
vi. Attribute : 3
vii. Source Element : SINT or INT data type tag
viii. Write D/O data to be set on 0th bit of Source element, SINT data
moved to appropriate bit by use of BTD instruction based on current
instance.

Reg,
NK

 

[Kanna006]

3. For DO data write,
i. Message Type : CIP Generic
ii. Service Type : Get Attribute Single Set Attribute single

 

[Ken Roach]

While I understand that you're pleased that you found a way to get your controller to run without a properly configured network architecture, you have made a very bad engineering decision.

The whole point of running I/O with implicit messaging is to allow the controller and its network modules to handle the connection, exchange, fault detection, and error handling onboard. This is literally their purpose.

It's even more critical when working with Redundancy systems, where the status of buffers and connections to a failed controller are broken unceremoniously when there's a switchover, but I/O connections are handled reliably by the communication modules and the Redundancy Modules.

Your system will not work as intended in the event of a Redundancy failover.

I urge you in the strongest possible terms to un-do your messaging logic and configure your network so that it compatible with ControlLogix Redundancy.