Mitsubishi Electric Q68TD-G-H02 MELSEC Q Series Thermocouple Input Module

SKU Q68TD-G-H02

In stock

12-month warranty
Free returns within 30 days

Manufacturer: Mitsubishi Electric
Product No.: Q68TD-G-H02
Origin United States
Product Type: PLC Temperature Input Modules
Payment: T/T, Western Union
Weight: 0.22 kg
Dimensions: 13 cm x 2.74 cm x 10.2 cm
Shipping port: Xiamen
Warranty: 12 months

Product Description

Description

Designed for high-precision temperature acquisition in demanding industrial environments, the Mitsubishi Electric Q68TD-G-H02 is a channel-to-channel isolated thermocouple input module for the MELSEC Q series PLC platform. This module supports up to 8 independent input channels, delivering robust protection against ground loops and common-mode electrical noise through dedicated transformer isolation. Built to handle standard sensor variations, it integrates native cold junction compensation (CJC) and precise analog-to-digital signal conversion parameters, making it an ideal choice for multi-zone furnace control, chemical processing, and plastic extrusion applications.

Key Features

High-Channel Isolation: Channel-to-channel and channel-to-CPU transformer isolation prevents cross-talk and ensures system stability under challenging electrical conditions.
Sensor Disconnection Detection: Independent diagnostic tracking triggers warning flags immediately when a sensor wire break is detected on any specific channel.
Broad Thermocouple Support: Compliant with international standards including JIS C1602-1995, IEC 60584-1, and IEC 60584-2.
Fast Update Cycle: Sampling and conversion complete within 640 ms across all 8 active channels.
Dynamic Temperature Scaling: Outputs 16-bit signed binary values representing physical measurement ranges from -2700 to 18200.

Applications

Multi-zone thermal processing ovens and industrial manufacturing furnaces.
Petrochemical and chemical reactor vessel thermal monitoring.
Plastic extrusion machines and injection molding hot-runner systems.
Power generation plant steam and bearing temperature diagnostics.

Technical Specifications

Parameter	Specification Value
Manufacturer	Mitsubishi Electric
Model Number	Q68TD-G-H02
Module Type	Channel-to-channel insulation thermocouple input unit
Input Channels	8 channels (plus cold junction compensation channel)
Digital Output Format	16-bit signed binary (-2700 to 18200)
Thermocouple Standards	JIS C1602-1995, IEC 60584-1 (1995), IEC 60584-2 (1982)
Resolution (B, R, S, N)	0.3 degC
Resolution (K, E, J, T)	0.1 degC
Sampling Cycle	320 ms / 8 channels
Conversion Speed	640 ms / 8 channels
Channel-to-Channel Insulation	Transformer insulation (1000 Vrms AC for 1 minute)
Channel-to-CPU Insulation	Transformer insulation (500 Vrms AC for 1 minute)
Insulation Resistance	10 MOhm or more at 500 VDC
Internal Current (5 VDC)	0.65 A
I/O Points Occupied	16 points (Intelligent function module)
External Interface	40-pin connector (Requires A6CON1, A6CON2, or A6CON4)
Module Dimensions	13 cm x 2.74 cm x 10.2 cm
Net Weight	0.22 kg
Shipping Weight	1.2 kg

Empirical Engineering Insights

Alternative Models & Compatibility

When migrating older Q-Series setups that utilize non-insulated modules (such as the standard Q64TD), the I/O assignment profiles must be revised in GX Works2 or GX Works3. Since the Q68TD-G-H02 utilizes a 40-pin connector interface rather than a screw-terminal block, direct drop-in replacement is not physically possible without rewiring or employing an external terminal conversion unit.

Application Pitfalls & Engineering Notes

While the module provides 1000 Vrms AC insulation between input channels, the cold junction compensation (CJC) sensor tracking circuit is non-isolated from the sequencer's internal power supply line. Ensure that temperature sensor shields are grounded correctly and keep them isolated from external power cabling to prevent capacitive coupling and potential drift in high-voltage industrial panels.

Commissioning & Wiring Tips

To avoid generating misleading channel-disconnection diagnostic codes, unused thermocouple input channels must be explicitly disabled in the intelligent function module parameter settings. If a channel remains enabled in the system configuration without a connected thermocouple, the module will permanently flag an open-loop system fault.

Installation Guidelines

CRITICAL WARNING: Prior to mounting or removing this module, isolate and switch off all external power supplies connected to the PLC rack and output loads. Failure to fully de-energize the assembly can cause unexpected diagnostic faults, internal component degradation, or hardware failure.

1 Power down the MELSEC Q base unit completely before inserting the module into the designated slot.

2 Hook the bottom tab of the module into the base unit's guide slot, then push the module firmly into place until the top latch clicks.

3 Secure the module lock screw (M3 size) to a torque of 0.36 to 0.48 N-m to guarantee continuous grounding contact.

4 Wired connections should be terminated using the compatible 40-pin connector (A6CON1/A6CON2/A6CON4). Shielded thermocouple extension wire must be routed separately from high-voltage AC lines.

Shipping & Returns

Global Express Shipping

Standard Delivery: 4–6 business days via DHL, FedEx, and UPS.
Express Dispatch: Same-day dispatch for in-stock orders placed before 2:00 PM (GMT+8).
Worldwide Coverage: Serving over 150 countries.

Returns & Warranty

30-Day Guarantee: Returns accepted for in-stock products in original, factory-sealed packaging.
12-Month Warranty: Every industrial component is backed by our technical warranty.

FAQ

What is the primary benefit of the channel-to-channel insulation on the Q68TD-G-H02?

It provides 1000 Vrms AC insulation between thermocouple input channels. This prevents ground loops, signal cross-talk, and noise interference when monitoring multiple grounded sensors across different process vessels.

Which thermocouple sensor types does this module support, and what are their resolution limits?

The module supports JIS C1602-1995 and IEC 60584 standards. For types B, R, S, and N, the conversion resolution is 0.3 degC. For types K, E, J, and T, the resolution is 0.1 degC.

How do you resolve false disconnection detection faults on unused channels?

Unused channels must be explicitly disabled in the GX Works parameter settings. If left active without a connected thermocouple, the integrated disconnection detection logic will trigger a channel-level fault.

What are the compatible external wiring connectors for this module?

The module uses a 40-pin interface. It requires separately sold connectors such as the A6CON1 (soldering type), A6CON2 (crimp type), or A6CON4 (pressure displacement type).

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