The QJ71WS96 is Mitsubishi Electric’s web server module for the MELSEC-Q programmable controller series, providing a built-in HTTP web server that enables browser-based monitoring and control of MELSEC-Q systems from any PC, tablet, or smartphone on the plant network — without requiring dedicated HMI hardware, SCADA software licences, or custom application development for basic production monitoring and remote diagnostics. By hosting customisable web pages directly on the module, the QJ71WS96 allows maintenance engineers and production managers to view real-time PLC data, machine status, and alarm information through a standard web browser over the plant Ethernet network, making it a cost-effective solution for remote monitoring of distributed MELSEC-Q systems where full SCADA deployment is not justified. Atlantech Drives holds stock of the QJ71WS96. Contact us for fast worldwide delivery and competitive pricing.
What Is the QJ71WS96?
The QJ71WS96 is a MELSEC-Q series intelligent communication module implementing an embedded HTTP web server, accessible from any web browser on the same Ethernet network. The module hosts user-customisable HTML web pages that display real-time MELSEC-Q CPU device data — bit device states (X, Y, M, B), word register values (D, W, R), and special registers (SD) — refreshed automatically at a user-configurable interval. Web page templates are created using Mitsubishi’s MX WebDesigner software and uploaded to the module’s internal flash memory, allowing custom monitoring screens to be developed without HTML programming skills. In addition to display-only monitoring, the QJ71WS96 supports write operations from the browser — operators can set bit devices, enter word register values, and trigger CPU operations via web browser input fields, enabling basic remote control without a dedicated HMI. The module also provides a built-in system monitor page showing CPU status, module error information, and network diagnostics for remote maintenance access.
Key Technical Specifications
- Model: QJ71WS96
- Function: Embedded HTTP web server for browser-based PLC monitoring
- Ethernet Interface: 100BASE-TX (RJ45), built-in
- Web Server Protocol: HTTP (HTTPS not supported on base model)
- Maximum Simultaneous Client Connections: 5
- Web Page Storage: Internal flash memory (user page capacity: approx. 5 MB)
- Data Refresh Rate: Configurable (minimum 500 ms refresh interval)
- Supported Devices: X, Y, M, B, T, C, D, W, R, SD (read and write)
- Maximum Data Points per Web Page: 128 device points
- User Authentication: Password-protected access (configurable)
- Current Consumption (5 VDC internal bus): 0.70 A
- External Power Supply: 24 VDC ±10%, 0.40 A (required)
- Operating Temperature: 0°C to 55°C
- Compatible CPUs: MELSEC-Q Universal model and H-model CPUs
- Weight: Approx. 0.30 kg
Typical Industrial Applications
The QJ71WS96 is widely deployed as a low-cost remote monitoring solution for geographically distributed MELSEC-Q systems where the monitoring requirement does not justify the cost of a full SCADA implementation. In water and wastewater treatment, QJ71WS96 modules installed in remote pumping stations allow operations staff at the treatment plant to monitor pump run status, flow totals, level readings, and alarm states from a browser on the control room workstation without requiring a dedicated communication link to each remote station beyond the existing plant Ethernet network. In building management and HVAC control applications, the QJ71WS96 provides facilities managers with browser access to chiller plant status, air handling unit run/fault data, and energy metering register values from any building network PC. In food and beverage production, QJ71WS96 modules installed in filling line controllers allow quality assurance engineers to view real-time production counts, fill weight averages, and rejection rates from their office workstations without interrupting the production operators at the HMI. The module is also commonly used during commissioning and site acceptance testing phases, where engineers need temporary remote access to PLC data from a laptop without connecting GX Works2 — the browser interface provides immediate read access to all device data without requiring GX Works2 installation on the accessing computer.
Troubleshooting Guide
If the QJ71WS96 web pages are not accessible from a browser, the diagnostic sequence begins with verifying basic Ethernet connectivity — ping the module’s configured IP address from the accessing PC to confirm the module is reachable on the network. If ping succeeds but the browser displays a connection refused error, verify that the module’s HTTP server is enabled in the MX WebDesigner configuration and that the correct TCP port (default 80) is not blocked by a plant network firewall or managed switch access control list. If ping fails, check the module’s IP address configuration in GX Works2’s network parameter settings and verify the IP address, subnet mask, and gateway are consistent with the plant network addressing scheme. For web pages that load but show stale data (values not updating), check the auto-refresh interval setting in MX WebDesigner — if the refresh interval is set longer than 10 seconds, data updates may appear infrequent. Also verify that the browser’s own caching is not preventing page refresh: use Ctrl+F5 (hard refresh) to bypass browser cache and confirm whether the data is actually stale or is a caching artefact. If certain device values display as dashes (–) rather than numeric values, the corresponding devices have not been configured in the web page’s device list in MX WebDesigner, or the device addresses reference a range not supported by the connected CPU model.
Frequently Asked Questions
Q: Can the QJ71WS96 be accessed from outside the plant network via the internet?
A: The QJ71WS96 supports HTTP only (not HTTPS), which means all data transmitted between the browser and the module is unencrypted. Direct internet exposure of the QJ71WS96 is strongly discouraged for security reasons. For remote access from outside the plant network, always use a VPN connection to the plant network and access the QJ71WS96 over the VPN — this provides encryption and authentication at the network level without requiring HTTPS support on the module itself.
Q: Can multiple users access the QJ71WS96 simultaneously from different browsers?
A: Yes, up to five simultaneous browser connections are supported. If a sixth user attempts to connect when five connections are already active, the connection is refused until one of the existing sessions is closed or times out. For applications requiring more than five simultaneous monitoring connections, a higher-capacity solution such as the QJ71MES96N with a SCADA database interface, or Mitsubishi’s iQ Works SCADA software, should be specified instead.
Q: Does the QJ71WS96 support write operations to PLC outputs from the web browser?
A: Yes, with appropriate access control. The QJ71WS96 supports browser-based write operations to bit and word devices, configurable per web page in MX WebDesigner. Write access can be restricted to specific device ranges and protected by a separate write password, independent of the read access password, to prevent unauthorised remote operation of machine outputs while still allowing unrestricted monitoring access.
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