Melsec MC 3E Data Collection Guide

Melsec MC 3E Data Collection Guide

1. Protocol Overview

  • Protocol Description: The MC 3E (Melsec Communication Protocol 3E) is a proprietary Ethernet communication protocol developed by Mitsubishi Electric for its Q, L, and iQ-R series PLCs. The protocol supports both Binary and ASCII data formats and utilizes TCP or UDP for transmission, enabling efficient read/write access to PLC internal data from host systems.
  • Application Scenarios: This protocol is widely used in Mitsubishi automation systems and serves as a mainstream communication protocol for data exchange and equipment monitoring between PLCs and systems such as HMI, SCADA, and MES.
  • E2C Trinity Support: E2C Trinity supports connecting to Mitsubishi PLCs using the MC 3E protocol via Ethernet (TCP/UDP), acting as a client to read and write data from various PLC memory areas, including X, Y, M, D, W, R, etc.

2. Prerequisites

Before starting the configuration, please ensure the following:

  • Hardware Connection:
    • Ensure the E2C Trinity gateway and the target PLC are connected to the same Local Area Network (LAN) and can communicate.
    • The debugging PC must be connected to the same network to log into the E2C Trinity web interface for configuration.
  • Network Parameters:
    • Obtain the IP Address and Port Number of the target PLC. The default port for the MC 3E protocol is typically 6000.
    • Ensure the E2C Trinity gateway is on the same subnet as the PLC with no IP conflicts.
  • Device Parameters:
    • Prepare the PLC project file or the Data Point List.
    • Identify key parameters:
      • Communication Mode: Confirm whether the PLC is configured for TCP or UDP, and whether it uses Binary or ASCII format.
      • Data Point Addresses: e.g., D100, M200.
      • Data Type for each point: e.g., bool, short (int16), float (float32), etc.

3. Configuration Steps

Follow these steps within the E2C Trinity web interface.

Step 1: Create Device

  1. Log into the gateway management page. Navigate to [Data Acquisition] to enter the E2C Trinity configuration page.


2. Click the "Create Device" button and fill in the connection information in the pop-up window.

Parameter Description Example
Name Unique identifier for the PLC device. Packaging-Line-A-Machine-02
Driver Select [MITSUBISHI] -> [MC 3E] from the dropdown list. MC 3E
Is Binary Select the data format; must match the PLC-side configuration. Yes
Connection Channel Select TCP or UDP; must match the PLC-side configuration. TCP
IP Address The IP address of the target PLC. 192.168.1.18
Port Number The MC 3E protocol port number of the PLC. 6000
Polling Cycle (s) Frequency of data requests (Seconds). 10
Description Additional info for user reference. Core equipment for Line A
Collection Timeout (ms) Timeout for the device to respond to requests. 1000
Connection Timeout (ms) Limit for establishing a TCP connection. 1000
 3.  Click "Save" to complete the device creation.

Step 2: Configure Tag (Point Table)

  1. Select the newly created device from the device list on the left.
  2. Click "Add" to create a single data acquisition Tag. Fill in the tag information.

Parameter Description Example
Name The tag name used in data reports. Temperature
Tag Type Device Tag: Data from the PLC.

Virtual Tag: Intermediate gateway-side variable.		 Device Tag
Address Type Register type in the PLC (e.g., M, X, Y, D, W, R). + For example, if the point address in the PLC is D100, configure the "Address Type" as "D" and the "Address" as "100".
+ For example, to read the 3rd bit of the D100 register in the PLC, configure the "Address Type" as "D", the "Address" as "100", and the "Bit Offset" as "3".
Address Specific register address in the PLC.
Bit Offset Required only for 'bool' types; specifies the bit index.
Data Type Must match the PLC's data format. float (float32)
Read/Write Permission Read Only or Read/Write (for remote modification). Read Only
Decimals Number of decimal places (for float/double). 2
Unit Engineering units (e.g., °C, KPa, mm). °C
Associated Group Assign the tag to a specific data group. -
Description Brief explanation of the tag's purpose. Reactor Real-time Temp
Data Operation Mathematical processing (Scaling, Offset, etc.). None

Repeat for all tags. Once finished, click "Publish" in the top right corner to apply the configuration.

4. Verification & Troubleshooting

Verification

  1. Check the device list to ensure the status is Online and tags are being collected.

2. Check whether the collected values are correct.

 3. Test Writing: Click the edit icon in the "Latest Value" column to modify the value. The next update should reflect the change.

Common Troubleshooting (FAQ)

  • Issue: Device status is "Offline" or connection failed.
    • Check physical cable connections and link lights.
    • Use the Ping tool in [System -> Tools] to check network reachability.
    • Carefully verify the IP, Port, TCP/UDP mode, and "Is Binary" settings against the PLC configuration.
    • Check PLC Ethernet module settings; ensure a connection or port is configured for the host (E2C Trinity).
  • Issue: Device is connected, but tag values are null or incorrect.
    • Verify Address and Data Type: Ensure the "Address Type" (e.g., D, M), "Address" (e.g., 100), and "Data Type" (e.g., short, float) match the PLC program exactly.
    • Ensure the addressed register exists and the PLC program is running.
    • Check [Debug Logs] to filter by device and identify specific error details.
  • Issue: Where to check logs?
    • Check Debug Logs or System Logs in the management interface.

5. Appendix

Mitsubishi MC 3E Data Type Mapping

When configuring tags in E2C Trinity, use the following mapping:

E2C Trinity Type Length / Sign PLC Equivalent Example Address Notes
bool 1 bit Bit M, X, Y, B, L Read single bit, e.g., M100.
ushort (uint16) 16 bit, Unsigned Word (Unsigned) D, W, R, SD, SW 16-bit word, e.g., D100.
short (int16) 16 bit, Signed Word (Signed) D, W, R, SD, SW 16-bit signed word, e.g., D101.
uint (uint32) 32 bit, Unsigned Double Word (Unsigned) D, W, R, SD, SW 2 consecutive addresses, e.g., D102.
int (int32) 32 bit, Signed Double Word (Signed) D, W, R, SD, SW 2 consecutive addresses, e.g., D104.
float (float32) 32 bit REAL (Floating point) D, W, R, SD, SW 2 consecutive addresses, e.g., D106.
string N Bytes String D, W, R Check PLC storage method and length.

Revision History

Version Date Author Changes
1.0 2025-09-22 Ken Li Initial document creation.

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