Performance Limits for 27,000+ Modbus TCP/IP Tags

Ignition
1

Hello Ignition Community,

We are currently planning a new SCADA project utilizing Ignition, and we have some questions regarding the performance of large-scale Modbus communication. We would greatly appreciate any shared experiences or official recommendations from Inductive Automation experts in the community.

Project Overview

  • Protocol: Modbus TCP/IP

  • Driver: Using the native Ignition Modbus TCP/IP driver only.

  • Estimated Total Tags: Approximately 27,000 tags.

Core Performance and Connectivity Questions

We primarily need to determine the limits of a single Gateway and how to optimize for performance. We have the following specific inquiries:

  1. Single Gateway Load Capacity:

    • Can a single Ignition Gateway instance reliably and efficiently handle 27,000 Modbus TCP/IP tags?

    • What is the recommended minimum scan rate (in milliseconds) we should target under this load to ensure system stability and maintain reasonable communication latency?

  2. Device Connection Limit:

    • What is the theoretical or recommended maximum number of independent devices (Modbus Servers/PLCs) that the Ignition Modbus TCP/IP driver should simultaneously connect to? Should we aim to distribute the connections across as many devices as possible?

We look forward to your helpful responses and discussion!

Thank you all!

2

Is this architecture all on a LAN or polled over e.g. 4G infrastructure?

3

  1. There's no specific tag limit. Big server hardware should be able to handle hundreds of thousands of tags. Your Modbus devices are more likely to be the bottleneck than Ignition. You can easily poll at 500ms. Going much faster may require some network analysis (latency matters).

  2. There's no specific device limit. It would be easiest to manage if you used many tags per device and used Modbus TCP concurrency to tweak performance.

You should use Ignition's 2-hour trial mode to mock up what you need.