Technical Solution for Data Bridging Between Pro-face HMI and AB PLC

In the field of industrial automation, transmitting data from third-party devices through a Human-Machine Interface (HMI) to a Programmable Logic Controller (PLC) is a common requirement. Drawing on OUKE Automation's extensive experience, this article explores the specific application scenario of Pro-face GP Pro EX HMI and Allen-Bradley ControlLogix/CompactLogix PLC communicating via EtherNet/IP protocol and reading data from Modbus TCP devices. Two technically validated solutions are presented.

Project Background Analysis

The current system architecture consists of a Modbus TCP level sensor, a Pro-face HMI, and an Allen-Bradley PLC. Although the HMI can successfully acquire and display data from the level sensor, the next step is to forward this information to the PLC processor running on the Studio 5000 platform. This type of integration issue involving different brand products is quite common among the many international clients served by OUKE.

Solution Overview

Solution A: Utilizing HMI Built-in Gateway Features

This method leverages the HMI's powerful data routing capabilities, achieving high stability without the need for additional coding. We have verified the effectiveness of this approach in over twenty similar cases.

• Configuration Steps:

• Create a new driver instance for Allen-Bradley Ethernet/IP in the GP Pro EX development environment.

• Ensure the correct PLC IP address and corresponding slot number are entered.

• Save the settings and activate the newly created driver.

• Through the "Gateway" or "Routing" menu item (which may vary depending on the software version), add a new mapping rule. Specify the source address as a specific location in the Modbus holding register (e.g., 40001) and the target as the corresponding PLC tag (e.g., Tank_Level).

• Activate the mapping relationship, and the data will automatically sync to the PLC without any additional coding.

Solution B: Using Scripting Technology for Data Transfer

When dealing with older HMI models that do not support gateway features, this alternative strategy can be considered. OUKE's technical experts often use this method to address compatibility issues with discontinued equipment.

• Execution Process:

• First, establish two independent driver connections for Modbus TCP and EtherNet/IP.

• Define data tags in both to represent the sensor value and the corresponding PLC variable.

• Use the "Logic Control" tool to set up a periodic task with a fixed interval (recommended between 100 and 500 milliseconds) to perform the following operation: assign Sensor_Value to PLC_Level.

• Finally, save and start the task.

Implementation Guidelines

Based on OUKE's accumulated professional knowledge, we offer the following recommendations:

• Before starting, verify whether the HMI firmware includes the necessary gateway support, as this directly determines which strategy to choose.

• During the testing phase, ensure all network nodes are unobstructed, including but not limited to normal Ping test results between the HMI and PLC, and the default Modbus port 502 being open.

• Initially, it is advisable to start with a small dataset and gradually expand.

• If scripting is necessary, carefully adjust the execution frequency to avoid negatively impacting HMI performance.

• For potential hardware failures, OUKE commits to providing rapid response services.

Technical Support

Both approaches can effectively achieve the desired goals. The first solution, leveraging hardware-level optimization, demonstrates superior performance and is the preferred choice of OUKE. The second, while adding some system overhead, offers broad applicability. Regardless of the chosen method, OUKE provides 24/7 technical support, including a one-hour emergency response and a three-day solution delivery, ensuring your automation system remains in optimal condition.