The QJ71MES96N is Mitsubishi Electric’s MES (Manufacturing Execution System) interface module for the MELSEC-Q programmable controller series, providing direct database connectivity between the MELSEC-Q PLC and enterprise IT systems — including MES platforms, ERP systems, SCADA databases, and SQL-compatible data historians — without requiring intermediate PC-based OPC servers, custom middleware, or specialised integration software. As the hardware gateway for Mitsubishi’s iQ Mesenger integration solution, the QJ71MES96N enables MELSEC-Q controllers to read and write production data, recipe parameters, quality results, and machine status directly to SQL databases over standard Ethernet, bridging the OT/IT boundary that traditionally requires dedicated integration infrastructure. In stock at Atlantech Drives. Request your quote within 24-48 hours with worldwide shipping and 12-month warranty.
What Is the QJ71MES96N?
The QJ71MES96N is a MELSEC-Q series intelligent communication module implementing Mitsubishi Electric’s iQ Mesenger database connectivity protocol. The module connects to the plant Ethernet network via a built-in 100BASE-TX port and communicates directly with SQL-compatible databases — including Microsoft SQL Server, Oracle Database, MySQL, and IBM DB2 — using JDBC (Java Database Connectivity) or ODBC (Open Database Connectivity) database drivers installed on the module’s internal processor. The MELSEC-Q CPU writes production data (quantities produced, cycle times, quality measurements, alarm events) to designated buffer memory registers in the QJ71MES96N, and the module autonomously transmits this data to the configured database tables at configurable trigger conditions — on a timer, on a production event, or on a PLC data change. Similarly, the module can read recipe data, production orders, and configuration parameters from the database and make them available in the MELSEC-Q CPU’s device memory via the buffer memory auto-refresh mechanism. Configuration of database tables, SQL queries, and data mapping is performed using Mitsubishi’s MX MESInterface configuration software.
Key Technical Specifications
- Model: QJ71MES96N
- Function: MES/IT database interface (iQ Mesenger)
- Ethernet Interface: 100BASE-TX (RJ45), built-in
- Supported Databases: SQL Server, Oracle, MySQL, DB2 (via JDBC/ODBC)
- Maximum Database Jobs: 64 (simultaneous data exchange definitions)
- Maximum Data Points per Job: 2,048 device points per database job
- Communication Trigger: Timer, event-driven, or manual from CPU program
- Data Direction: Bidirectional (PLC to DB write, DB to PLC read)
- Security: User authentication, SSL/TLS encrypted communication supported
- Current Consumption (5 VDC internal bus): 0.85 A
- External Power Supply: 24 VDC ±10%, 0.50 A (required)
- Operating Temperature: 0°C to 55°C
- Compatible CPUs: MELSEC-Q Universal model CPUs
- Weight: Approx. 0.35 kg
Architecture & Design Overview
The QJ71MES96N implements a three-layer integration architecture that decouples the real-time PLC execution from the non-deterministic IT network communication. The PLC layer exchanges data with the module via the MELSEC-Q high-speed internal bus at scan cycle speed — writes to buffer memory from the CPU program are immediate and do not introduce scan time overhead. The module’s internal processor then manages the Ethernet communication with the database server asynchronously, queuing transactions and handling network retries without affecting PLC scan time. The database layer receives and processes SQL INSERT, UPDATE, and SELECT transactions generated by the module based on the job definitions configured in MX MESInterface. This architecture ensures that network delays, database server response time variability, or temporary network unavailability do not cause PLC scan time overruns or disrupt machine control logic — the module buffers up to 1,000 unsent database transactions internally and transmits them when connectivity is restored, preventing data loss during network interruptions. The «N» suffix in QJ71MES96N denotes an enhanced version of the original QJ71MES96 with improved SSL/TLS security support and expanded database compatibility compared to the original model.
Expert Tips
When designing the database job configuration for the QJ71MES96N, structure database writes as batch INSERT operations rather than individual row inserts where possible — batching multiple production records (cycle time, quantities, quality flags) into a single SQL INSERT transaction significantly reduces the database server load and network round-trip count compared to individual inserts per data point. For high-frequency data logging (more than 10 records per second), configure the QJ71MES96N to write to a local staging table on the database server with minimal indexing, and use a separate database job or stored procedure to move data from the staging table to the final production history table — this two-stage approach prevents index rebuild overhead from slowing the INSERT rate during high-frequency production. Monitor the QJ71MES96N’s unsent transaction buffer count via buffer memory in GX Works2 regularly during commissioning — if the buffer count grows continuously, the database server is not processing transactions fast enough for the configured logging rate, and either the logging rate or the database indexing strategy must be adjusted. For recipe download (database to PLC), always implement a handshaking protocol in the MELSEC-Q ladder program: use a dedicated «recipe download request» bit that the HMI or ERP system sets, and confirm receipt with a «recipe active» acknowledgement bit — this prevents partial recipe writes from taking effect if the database read job is interrupted mid-transfer.
Frequently Asked Questions
Q: Does the QJ71MES96N require a PC-based OPC server to connect to a SCADA system?
A: No. The QJ71MES96N connects directly to SQL-compatible databases over Ethernet without requiring an OPC server, PC middleware, or any intermediate software layer on the plant network. The module handles all database communication autonomously using its built-in JDBC/ODBC connectivity. For SCADA systems that use SQL databases for historian storage (such as Wonderware InSQL, OSIsoft PI via RDBMS interface, or Ignition’s built-in database logging), the QJ71MES96N can write production data directly to the SCADA historian database without SCADA software involvement in the data collection path.
Q: Can the QJ71MES96N connect to a cloud-based database such as Microsoft Azure SQL or Amazon RDS?
A: Yes, provided the plant network has outbound connectivity to the cloud endpoint and the appropriate SSL/TLS certificates are configured. The QJ71MES96N supports SSL/TLS encrypted database connections, which is required for most cloud database services. Network latency to cloud databases (typically 20–100 ms depending on geography) must be accounted for in the database job timeout settings — configure job timeout values at least 5× the expected network round-trip time to prevent spurious timeout errors during peak network load periods.
Q: What is the maximum data logging rate achievable with the QJ71MES96N?
A: The maximum sustained database write rate depends on the database server performance, network latency, and SQL transaction complexity. Under typical conditions with a local SQL Server database and simple INSERT statements, the QJ71MES96N can sustain approximately 50–100 database transactions per second. For higher logging rates, Mitsubishi recommends using the module’s batch write function, which consolidates multiple data points into a single transaction, effectively multiplying the data throughput for a given transaction rate.
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