The QD62E is Mitsubishi Electric’s 2-channel high-speed counter module for the MELSEC-Q programmable controller series, providing pulse counting at up to 500 kpps per channel with built-in coincidence output — generating a hardware output signal the instant the counter value matches a preset comparison value, without waiting for the CPU scan cycle. As the enhanced variant of the QD62 counter module family with coincidence detection output, the QD62E is the preferred specification for applications requiring immediate hardware response to position or count threshold events — such as cam switching, electronic limit switches, print registration, and cut-to-length control — where the 5–50 ms response latency of software-based threshold detection in the CPU program is unacceptable. Available now at Atlantech Drives with worldwide express delivery and 12-month warranty — complete our quote form for pricing and availability.
What Is the QD62E?
The QD62E is a MELSEC-Q series intelligent function module providing two independent channels of high-speed pulse counting at up to 500 kpps, each with an associated coincidence output circuit that activates a hardware output relay or transistor when the channel’s count value matches a user-defined comparison value stored in the module’s buffer memory. The coincidence output response time is less than 0.1 ms from the counter reaching the comparison value to the output activating — compared to the 5–50 ms response time achievable through CPU scan-based threshold comparison — making the QD62E essential for high-speed process control where machine mechanical timing requires sub-millisecond output activation precision. Each channel accepts AB quadrature, single-phase, or CW/CCW pulse inputs from incremental encoders, photoelectric sensors, or pulse generators, with a configurable count multiplication factor (×1, ×2, ×4) for quadrature inputs. The module interfaces with the MELSEC-Q CPU via the high-speed internal bus using FROM/TO instructions or GX Works2 auto-refresh for setpoint loading and count value reading.
Key Technical Specifications
- Model: QD62E
- Counter Channels: 2
- Maximum Count Frequency: 500 kpps per channel (single-phase); 500 kpps total in quadrature ×4 mode (125 kHz physical encoder frequency)
- Counter Input Types: AB quadrature (×1, ×2, ×4), CW/CCW, single-phase up/down
- Counter Range: -2,147,483,648 to +2,147,483,647 (32-bit signed)
- Coincidence Output: 1 output per channel (transistor, 24 VDC)
- Coincidence Output Response Time: Less than 0.1 ms from count match to output activation
- Comparison Values per Channel: 2 (upper and lower comparison values for window detection)
- Latch Input: External latch input per channel (captures count value on rising edge)
- Current Consumption (5 VDC internal bus): 0.40 A
- External Power Supply: 24 VDC ±10%, 0.15 A (required for coincidence output circuit)
- Operating Temperature: 0°C to 55°C
- Weight: Approx. 0.22 kg
Compatibility & System Integration
The QD62E is compatible with all MELSEC-Q CPU modules and base units and integrates with GX Works2 for buffer memory parameter configuration and online monitoring. The module’s coincidence output terminals are connected directly to the field device or control circuit that requires immediate activation — common connections include the cut knife solenoid valve trigger input in cut-to-length systems, the print head fire trigger in register-controlled printing, the label apply trigger in packaging, and the brake solenoid input in emergency positioning stop circuits. The coincidence output operates independently of the CPU scan cycle and continues to activate at the configured comparison value even during CPU STOP mode or program scan overrun conditions, providing reliable hardware output timing that cannot be disrupted by software events. For multi-axis systems requiring more than two coincidence output channels, multiple QD62E modules can be installed in the same base unit — each operating independently with its own comparison values and output circuits. The QD62E can also be used in combination with QD75 positioning modules in the same base unit — the QD75 manages the servo axis positioning while the QD62E provides high-speed coincidence detection for the secondary process trigger (such as a dispense trigger at a specific position during a servo-controlled XY traverse).
Installation Advice
The QD62E’s coincidence output response time of less than 0.1 ms is only achievable when the comparison value is pre-loaded into the module’s buffer memory before the counting operation begins — do not attempt to update the comparison value in real time during a high-speed counting operation, as the buffer memory write from the CPU program introduces a variable delay of up to one scan cycle between the CPU writing the new comparison value and the module loading it into the comparator circuit. For cut-to-length applications where the comparison value changes with each cut (different product lengths), pre-load the next cut position into the «next comparison value» register while the current cut is executing, and use the module’s comparison value swap function to activate the new value at the coincidence point — this ensures zero delay between the current cut output activation and the loading of the next comparison value. Route the coincidence output wiring directly to the actuated device using shielded cable, maintaining separation from power cables to prevent induced noise from triggering false coincidence outputs. For encoder input wiring, use differential line driver encoders (RS-422A) connected to the QD62E’s differential input terminals rather than open-collector encoders where possible — differential inputs provide superior noise immunity at high counting frequencies (above 100 kpps) where open-collector signal integrity becomes marginal in industrial electromagnetic environments.
Frequently Asked Questions
Q: What is the difference between the QD62E and the QD62D high-speed counter module?
A: The QD62E and QD62D both provide 2-channel high-speed counting at 500 kpps with coincidence output, but differ in their encoder input type support. The QD62E accepts standard 5V differential (RS-422A) or 12/24V single-ended encoder signals, while the QD62D is specifically designed for SSI (Synchronous Serial Interface) absolute encoder input in addition to incremental pulse input — the QD62D is specified when absolute position must be read from an SSI absolute encoder at power-up without a home return cycle. For systems using standard incremental encoders, the QD62E is the appropriate choice; for SSI absolute encoder systems, specify the QD62D.
Q: Can the QD62E coincidence output be used to trigger a servo drive’s torque limit function at a specific position?
A: Yes. The QD62E coincidence output can be wired directly to a servo drive’s torque limit input (such as the MR-J4’s TL1/TL2 torque limit selection input) to switch the drive from normal torque mode to a reduced torque limit at a precise position — a technique used in pressing, clamping, and insertion applications where the drive must approach a workpiece at full torque and then reduce torque to a controlled insertion force at a specific position. The 0.1 ms coincidence output response ensures that the torque limit activates at the correct mechanical position rather than at the next CPU scan cycle.
Q: What happens to the QD62E coincidence output if the CPU enters STOP mode while counting is active?
A: The QD62E’s coincidence detection and output circuit continue to operate independently of the CPU state — if the CPU enters STOP mode while the counter is active, the QD62E continues counting and will activate the coincidence output when the count reaches the comparison value, regardless of CPU mode. This ensures that machine timing is not disrupted by CPU mode changes during maintenance or program updates. Configure the coincidence output’s hold or clear behaviour on CPU STOP via the buffer memory parameters if specific safe-state output behaviour is required during CPU maintenance modes.
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