Is the DH+ protocol by Allen Bradley known as a routable protocol?
The MSG instructions are commonly known as "multihop" in the tech world.
Reviewing the history of register-based AB protocols, it becomes evident that the foundation was laid with the serial protocol DF1, which served as the 'mother tongue' for these systems. The flexibility of DF1 allowed for its use in a multi-drop configuration, thanks to the incorporation of a 1-byte ID number in the data packet. This protocol had strong ties to the earlier Modbus protocol. Although initially non-routable due to its reliance on the ID number for communication, DF1 evolved to adapt to modern networking technology. With the introduction of high-speed systems like DH+ and the transition to Ethernet-based communication, DF1 packets were adapted to fit into different network architectures. The incorporation of DF1 into Ethernet frames enabled PLCs to communicate over long distances using TCP/IP protocols. The integration of DF1 into CIP-protocol ethernet messages, known as 'PCCC', further expanded the capabilities of the system, allowing for complex routing scenarios involving multiple network modules. While the intricacies of these protocols were not openly published by AB, dedicated programmers were able to reverse engineer the systems to understand their functionality. The ability to transmit data over the internet to various network modules showcases the adaptability and scalability of AB's messaging protocols. In conclusion, the evolution of DF1 protocols from their origins in PLC-2 and 3 to their integration into modern Ethernet-based systems highlights the continuous innovation in industrial automation. The complexity of these protocols is balanced by AB's efforts to simplify them for PLC programmers, making advanced networking solutions accessible to a wider range of industries.
It appears to be a question related to specification compliance, and it would be beneficial to understand the rationale behind it. The DH+ protocol includes features such as "link IDs" and "Remote Addresses" in the PCCC packet, allowing for connections between DH+ networks or a DH+ and DH485 network. This interconnection of DH+ networks can be considered as an "internetworking" capability and may meet the criteria of a routable protocol. Additionally, the use of 1756-series Ethernet or ControlNet modules to emulate DH+ link transport and establish a CIP Path between two DH+ networks could also qualify as a routable protocol. A previous discussion by Power_plcdummy touched on troubleshooting legacy communication issues involving KF2 modules. Similarly, addressing the specific details of this current question rather than seeking a generic solution may yield better results.
I want to express my gratitude to everyone who has provided feedback on my previous posts. Although I am not knowledgeable in PLC systems, I am eager to learn from your responses. This discussion pertains to the NERC CIP requirements regarding critical infrastructure protection. When dealing with a system that utilizes a "routable protocol," it is crucial to implement various security measures. Conversely, if the system does not use a routable protocol, cybersecurity measures can be less stringent. For example, my setup involves SLC 5/04 and SLC 5/05 communicating via DH+ and DF1 protocols in a serial connection. Serial connections are typically not routable unless they are converted to a routable medium like TCP/IP or Ethernet, which I have not done in my case. Both ends of the connection remain serial.
No, the DH+ protocol by Allen Bradley isn't considered a routable protocol. It's more like a local network protocol chiefly used for communicating within a specific localized system, instead of sending data over broad networks. Meaning, it does not have the ability to determine the optimal path or handle the demands of a complex, large-scale network that comprises of various interconnected subnetworks - which is essentially the functionality of routable protocols.
Actually, the DH+ protocol by Allen Bradley is not considered a routable protocol. It is a proprietary local area network protocol designed for industrial automation processes that need critical response times. Its limitations in routing and network size have largely been replaced by Ethernet/IP in modern systems.
Great question! The DH+ protocol used by Allen-Bradley is actually classified as a token-passing protocol rather than a routable one. It enables communication between devices over a shared bus, but it doesn’t involve routing like TCP/IP does, so it's more about local network communication within a specific system. This is important to consider when designing industrial networks since it affects how devices can communicate and the scalability of the system.
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Answer: - No, the DH+ protocol by Allen Bradley is not considered a routable protocol. It operates at the Data Link layer of the OSI model and does not have built-in routing capabilities. Communication over DH+ typically requires direct point-to-point connections between devices.
Answer: - The DH+ protocol by Allen Bradley operates at the Data Link layer of the OSI model. It provides a communication platform for devices within a local network, but it does not have the ability to route data across multiple networks.
Answer: - No, DH+ protocol communication is not routable across different networks. It is primarily designed for communication within a single network or domain, and does not support routing data across multiple networks.
Answer: - Yes, Allen Bradley offers other protocols such as Ethernet/IP which support routing capabilities for communication across different networks. Ethernet/IP is a more commonly used protocol for industrial automation applications requiring routed communication between devices.
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