MAC36NL - Modbus - Optimizing the MAC36NL Modbus TCP network performance

Introduction

In large Modbus TCP networks with MAC36LN devices, optimizing network performance is key for efficient endpoint management. This includes maintaining polling frequencies and managing bandwidth effectively to improve system responsiveness and reliability.

Good Practice

To optimize network performance in systems using MAC36LN devices for Modbus TCP follow these best practices:

1. Set Poll Frequencies Appropriately: Ensure that the poll frequency for each point is set according to the requirements of the network and the capabilities of the devices. The default setting is typically 5 seconds, but this may need adjustment based on specific network conditions and performance expectations.

2. Manage Network Bandwidth Efficiently:

   • Device Connectivity: Utilize switches instead of hubs to connect devices as switches support ARP protocols that efficiently manage bandwidth by directing data frames to the correct ethernet interface channel.

   • Separate Protocol Traffic: If possible and necessary, you can make use of 2 MAC36NL’s ethernet ports and separate different types of traffic (e.g., Modbus TCP from BACnet or FOXs) onto different ports to prevent bandwidth competition among protocols. This separation ensures that each protocol gets the full bandwidth capacity of the port it is assigned to.

   • Quality of Infrastructure: Use high-quality patch cords and ethernet cables, preferably of a higher category, to avoid bandwidth limitations. Ensure that ethernet cables are not laid parallel to power cables to reduce electromagnetic interference.

   • Cabling Practices: Adhere to best cabling practices such as proper grounding of cable shields and using high-quality connectors to minimize data transmission errors and improve overall network stability.

3. Optimize Data Requests:

   • Addressing Registers: Group adjacent register addresses whenever possible. This grouping allows the MAC36LN to request multiple data points in a single frame, reducing the number of frames transmitted and improving the efficiency of data retrieval.

4. Utilize Diagnostic Tools: Employ tools provided by Niagara for diagnostics to analyze the current network setup and identify if there is any available bandwidth. Monitoring tools Poll Scheduler can be helpful. Indicators such as 'Busy time' can help in determining the efficiency of the network and guide necessary adjustments.