I am currently configuring a redundant ControlLogix system that needs to communicate with a remote SLC PLC. However, Rockwell has stated that SLC messaging is not supported with the redundant ControlLogix setup. Is there a solution for this issue so that the program code can receive the necessary value from the remote site? Any assistance would be greatly valued.
The redundancy feature in Logix 5580 (L8xE) does not allow for SLC messaging. In order to access this data and transfer it to Redundancy, it is recommended to utilize a different PLC. This PLC can either operate independently or be located within the 1756 IO chassis.
Utilize a bridge controller for communication between a redundant PLC and an SLC (System Level Controller). The PLC sends messages to the bridge controller through EIP, which can then communicate with the SLC (specifically a 505 model) using the native PCCC protocol. If using an older SLC 504, communication can also be established using DH+. Please note that "Conn" is a quicker typist.
I am currently facing a similar issue with my SLC5/05, which is actually a third-party device and not a true SLC. It appears that creating a "Generic CIP" message could be the solution to moving forward. While I have found ample information on using Modbus for this task, there is a lack of resources on implementing "Generic CIP" messaging for SLCs. My remote device does support Modbus, and I am utilizing an L306 as a bridge. Does anyone have experience with using Generic CIP for SLCs?
Learn about the SLC typed message formats detailed in document 1756-PM020, with a specific reference to page 79 containing information on SLC read A2.
It intriguing to see your effort to configure a redundant ControlLogix system that needs to communicate with a remote SLC PLC. However, from my past experience, the ControlLogix platform doesn't inherently support redundancy with SLC messaging. You might want to consider using something like a ProSoft MVI56E gateway module in your Controllogix rack, which can interface with SLCs and move the necessary data into ControlLogix. This module essentially "translates" between the PLC-5/SLC and ControlLogix platforms, facilitating the communication you need. Just ensure that your project requirements can handle this extra piece of hardware. Good luck with your project!
Although it's a bit tricky, there are workarounds for this. For instance, you could use a communication bridge such as Prosoft's Modbus module in the ControlLogix rack. This can communicate with both your ControlLogix and the SLC via Modbus. That way, the SLC could essentially be "translated" for the ControlLogix setup. It may require some additional configuration, but it should help to facilitate the communication you're in need of.
You might be able to use Rockwell's produced and consumed tags for this situation. If the SLC can communicate with a non-redundant ControlLogix PLC, then you could use that one as a kind of communication bridge. Set the SLC to update a set of tags in the ControlLogix, and have the redundant system consume those tags. It's a workaround, but depending on how time sensitive your data is, it could be an effective solution.
You might want to consider an intermediate unit that is capable of communicating with both systems. An intermediary PLC, or a gateway device as they're often called, can interface between the ControlLogix and the SLC PLC. This way, the ControlLogix system can fetch the needed data from the gateway device instead of directly from the SLC, and thus bypass the issue with lack of support for SLC messaging in the redundant ControlLogix setup. You'd need to ensure this doesn't introduce unacceptable latency though, so it might be worth testing this approach in a safe, controlled environment before implementing.
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Answer: - No, Rockwell has stated that SLC messaging is not supported with the redundant ControlLogix setup.
Answer: - One possible solution could be to explore alternative communication methods or protocols that are supported by both systems.
Answer: - Consider implementing a workaround or intermediary system to facilitate the exchange of data between the ControlLogix system and the remote SLC PLC.
Answer: - It may be beneficial to consult Rockwell's technical support or documentation for guidance on alternative communication solutions or workarounds in this scenario.
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