The Q64TCRTN is Mitsubishi Electric’s 4-channel thermocouple input temperature control module for the MELSEC-Q programmable controller series, integrating thermocouple signal conditioning, PID temperature control calculation, and analogue output generation in a single intelligent function module — providing complete closed-loop temperature control for up to four independent zones without requiring separate temperature controllers, analogue input modules, or analogue output modules. Designed for injection moulding machines, extruders, industrial ovens, and process heating systems where multiple temperature zones must be controlled precisely and independently from a single MELSEC-Q slot, the Q64TCRTN delivers thermocouple-to-output temperature control in a highly integrated, space-saving format. Atlantech Drives holds stock of the Q64TCRTN. Contact us for fast worldwide delivery and competitive pricing.
What Is the Q64TCRTN?
The Q64TCRTN is a MELSEC-Q series intelligent function module combining four thermocouple input channels with four corresponding analogue output channels (voltage or current) under independent PID control. Each of the four channels operates as a complete closed-loop temperature controller: the module reads the thermocouple temperature, compares it to the setpoint stored in the module’s buffer memory, executes the PID algorithm, and generates a proportional analogue output signal to the heating or cooling actuator — all within the module itself, without loading the CPU scan cycle with temperature control calculations. The CPU communicates setpoints and reads process values via FROM/TO instructions or GX Works2 auto-refresh, while the module handles the real-time control loop autonomously at a fixed sampling period. The Q64TCRTN supports type K, J, R, S, B, E, T, N, and PL II thermocouples, covering the full range of industrial temperature measurement applications from cryogenic to high-temperature furnace processes.
Key Technical Specifications
- Model: Q64TCRTN
- Control Channels: 4 (independent PID per channel)
- Input Type: Thermocouple — K, J, R, S, B, E, T, N, PL II
- Temperature Range: Dependent on thermocouple type (e.g., K type: -200°C to +1372°C)
- Input Resolution: 0.1°C (±0.3°C accuracy at 25°C ambient)
- Control Algorithm: PID with autotuning function
- Output Type: Voltage (0–5 VDC, 0–10 VDC, 1–5 VDC) or Current (4–20 mA, 0–20 mA) per channel
- Output Resolution: 12-bit
- Sampling Period: 500 ms per channel (standard mode)
- Cold Junction Compensation: Built-in
- Isolation: Optical, input to internal bus and output to internal bus
- Current Consumption (5 VDC internal bus): 0.60 A
- External Power Supply: 24 VDC ±10%, 0.40 A (required)
- Operating Temperature: 0°C to 55°C
- Weight: Approx. 0.28 kg
Architecture & Design Overview
The Q64TCRTN implements a distributed control architecture in which the PID calculation and output generation for all four channels are handled by the module’s internal microprocessor, operating independently of the MELSEC-Q CPU’s scan cycle. This architecture provides two key performance advantages: first, the temperature control loop executes at a fixed 500 ms sampling period regardless of CPU scan time or communication load — ensuring consistent control response even in systems where the main CPU scan time varies due to complex ladder programs or heavy network communication. Second, the CPU is relieved of PID calculation overhead, which would otherwise consume significant scan time in systems controlling four or more temperature zones. The module’s built-in cold junction compensation circuit continuously measures the module terminal temperature and applies the appropriate compensation to each thermocouple reading, eliminating the need for external cold junction compensation devices. The autotuning function determines the optimal P, I, and D parameters for each channel independently by executing a step response test on the controlled process — this single-button autotuning procedure, initiated via a buffer memory flag from GX Works2, eliminates the need for manual PID parameter calculation and is particularly useful for processes where the thermal time constant is unknown.
Expert Tips
When commissioning the Q64TCRTN in a new installation, always run the autotuning function before switching to automatic PID control — default PID parameters will not provide stable control for most industrial heating processes, and starting with poorly tuned parameters risks temperature overshoot that can damage the controlled product or process equipment. Initiate autotuning at a setpoint representative of normal operating temperature rather than at maximum setpoint, as the autotuning algorithm identifies PID parameters optimised for the setpoint at which it is run. For multi-zone systems where zones have significantly different thermal masses (such as an extruder with a small nozzle zone and a large barrel zone), run autotuning independently for each zone — do not assume that parameters tuned for one zone will provide adequate control for another. When wiring thermocouple inputs, use proper thermocouple extension cable (matched to the thermocouple type) from the sensor to the Q64TCRTN terminal — using standard copper wire for any portion of the thermocouple circuit between the sensor junction and the module terminal introduces a spurious thermoelectric EMF that causes a fixed temperature measurement error. Verify thermocouple polarity before power-up: a reversed thermocouple connection causes the module to read a temperature that falls as the process heats up, which will drive the output to maximum and potentially cause a runaway heating condition.
Frequently Asked Questions
Q: Can the Q64TCRTN control cooling as well as heating processes?
A: Yes. The Q64TCRTN supports both heating-only and heating/cooling control modes. In heating/cooling mode, the module generates a positive analogue output signal for heating actuators and a separate negative output (or a second channel’s output) for cooling actuators, implementing a split-range control scheme. The heating and cooling PID parameters can be set independently for each channel, accommodating processes where the heating and cooling dynamics differ significantly. Configure the heating/cooling control mode via the buffer memory parameters in GX Works2’s intelligent function module parameter editor.
Q: What thermocouple types does the Q64TCRTN support, and which is recommended for injection moulding barrel temperature control?
A: The Q64TCRTN supports K, J, R, S, B, E, T, N, and PL II thermocouple types. For injection moulding barrel temperature control in the typical 180°C to 350°C range, type J (iron-constantan) and type K (chromel-alumel) thermocouples are both commonly used. Type K is the more widely available and generally recommended choice for new installations due to its broader temperature range (up to 1372°C) and better resistance to oxidation at elevated temperatures compared to type J. Type J is acceptable for lower-temperature barrel zones but should not be used above 760°C due to oxidation of the iron element.
Q: Can the Q64TCRTN operate if the CPU is in STOP mode?
A: Yes. The Q64TCRTN continues executing its PID control loop and maintaining its output even when the MELSEC-Q CPU is in STOP mode, as the module’s control processor operates independently of the CPU. However, the CPU cannot update setpoints or read process values while in STOP mode. For safety-critical applications, configure the module’s output hold/clear behaviour on CPU STOP via the buffer memory parameters — setting the output to clear (0 V or 0/4 mA) on CPU STOP is recommended for heating applications to prevent uncontrolled heating during CPU maintenance or program modification.
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