Description
Configured for precise thermal monitoring, the Mitsubishi Electric Q68TD-G-H01 delivers eight channel-isolated thermocouple inputs to high-reliability MELSEC Q Series control environments. This high-performance module is designed to eliminate ground loops and reduce noise interference in multi-point temperature measurement applications, making it highly suitable for demanding industrial processing plants. Each channel can be configured independently, allowing for versatile sensor integration across different thermocouple types within a single PLC rack footprint.
Features
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Channel-to-Channel Isolation: Complete galvanic isolation between input channels prevents ground loop electrical interference and protects sensitive control systems.
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Multi-Type Thermocouple Support: Directly compatible with standard thermocouple types B, E, J, K, N, R, S, and T.
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Compact System Footprint: Occupies only 16 I/O points on the MELSEC Q base unit, conserving valuable slot space.
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Integrated Diagnostics: Offers sensor wire breakage and disconnection detection to trigger immediate system alerts and prevent thermal runaway.
Applications
- Plastic extrusion, molding, and hot runner thermal profiling.
- Heat treatment, kilns, and annealing industrial furnace control systems.
- Multi-zone chemical reactor vessel temperature tracking.
- Boiler feed-water and steam temperature monitoring in utilities.
Technical Specifications
| Manufacturer |
Mitsubishi Electric |
| Model Reference |
Q68TD-G-H01 |
| Series |
MELSEC Q Series |
| Module Type |
Temperature Input Module (Channel-Isolated) |
| Number of Inputs |
8 channels |
| Input Sensor Types |
Thermocouple (B, E, J, K, N, R, S, T) |
| Occupied I/O Points |
16 points (allocated as intelligent function module) |
| Internal Current Consumption |
0.49 A (at 5 VDC) |
| Module Width |
27.4 mm |
| Module Height |
98.0 mm |
| Module Depth |
90.0 mm |
| Net Weight |
0.18 kg |
| Shipping Weight (Calculated) |
0.50 kg |
Empirical Engineering Insights
Alternative Models & Compatibility
The Q68TD-G-H01 offers upgraded channel-to-channel isolation compared to non-isolated temperature modules such as the standard Q64TD. When replacing older non-isolated versions, review rack power budgets, as the internal 5 VDC current consumption is significantly higher (0.49 A) due to the onboard isolation circuitry. Ensure your system's power supply module (e.g., Q61P) has sufficient remaining overhead.
Application Pitfalls & Engineering Notes
To prevent measurement drift in environments subject to rapid ambient temperature fluctuations, avoid mounting the module directly adjacent to heat-producing components like power supplies or motor starters inside the enclosure. Ensure that unused input channels are software-disabled in the module parameters to prevent false sensor wire-breakage alarms and unnecessary CPU diagnostics.
Commissioning & Wiring Tips
Always use dedicated thermocouple extension and compensation cables matching the thermocouple type (e.g., KX extension wire for Type K sensors). Keep these sensor wires routed away from high-voltage AC cables and variable frequency drive outputs to minimize electromagnetic induction. Ensure shield wires are terminated at a single, clean instrumentation ground point near the PLC rack.
Installation Guidelines
CRITICAL WARNING: Disconnect all external power sources supplying the PLC system and any field-side wiring loops before inserting or removing the module. Performing installation tasks on an energized backplane risks destroying the sensitive internal isolation optocouplers and can cause unpredictable system operations.
1
Hook the bottom tab of the Q68TD-G-H01 module securely into the mounting slot of the MELSEC Q series base unit.
2
Pivot the module flush against the base plate and tighten the top securing screw to the specified torque rating to ensure solid ground plane contact.
3
Wire the thermocouple leads directly to the module terminals, maintaining strict attention to physical polarity indications (+ and - markings).
4
Configure the hardware configuration utility within your programming software (GX Works2 or GX Works3) to recognize the module and download parameter changes to the CPU.