The Q64DA is Mitsubishi Electric’s 4-channel analog output module for the MELSEC-Q programmable controller series — providing 4 independently configurable analog output channels with 12-bit resolution (4,096 counts) for voltage (0–10 VDC, ±10 VDC) and current (0–20 mA, 4–20 mA) signal generation, enabling MELSEC-Q systems to command variable-speed drives, proportional control valves, setpoint transmitters, and other analog-controlled field devices directly from the Q-series base unit without external D/A conversion hardware. In stock at Atlantech Drives. Request your quote within 24-48 hours with worldwide shipping and 12-month warranty.
What Is the Q64DA?
The Q64DA is a MELSEC-Q series intelligent function module providing 4 analog output channels for D/A conversion of digital setpoint values from the MELSEC-Q CPU to analog output signals for field device control. The module installs in any intelligent function module slot in a Q-series main or extension base unit, with the Q-series CPU writing digital output values to the Q64DA’s buffer memory (BFM) using TO instructions or the GX Works2 auto-refresh parameter for automatic data transfer each scan cycle. Each of the 4 channels can be independently configured for voltage output (0–10 VDC, ±10 VDC) or current output (4–20 mA, 0–20 mA) by parameter settings in GX Works2’s intelligent function module parameter editor — the output type selection is stored in the Q64DA’s non-volatile parameter memory and applies at each power-up without requiring re-configuration by the CPU program. The Q64DA provides superior specifications compared to the FX3U-4DA for MELSEC-Q applications: the Q-series module architecture provides faster auto-refresh data transfer via the Q-series internal bus versus the FX3U’s special function module FROM/TO instruction approach, enabling the Q64DA’s output values to be updated every CPU scan cycle without ladder programming overhead. The Q64DA’s 4 output channels cover the majority of multi-drive speed command, multi-valve control, and multi-setpoint applications requiring analog output from a MELSEC-Q system.
Key Technical Specifications
- Model: Q64DA
- Analog Output Channels: 4
- Output Signal Types: 0–10 VDC, ±10 VDC, 4–20 mA, 0–20 mA (per channel, selectable)
- Resolution: 12-bit (4,096 counts)
- Conversion Accuracy: ±0.3% of full scale (at 25°C) — better than FX3U-4DA’s ±0.5%
- Output Update Time: Approx. 1 ms per channel (4 ms total for 4 channels)
- Voltage Output Drive: Minimum 1 kΩ load impedance (10 mA maximum output current)
- Current Output Drive: Maximum 750 Ω load impedance
- Isolation: Between channels and Q-series internal bus (optical isolation)
- Compatible CPUs: Q02UCPU and compatible Q-series Universal/High Performance CPUs
- Installation: Q-series base unit intelligent function module slot
- Power Consumption: 5 VDC internal bus, approx. 0.28 A
- Operating Temperature: 0°C to 55°C
- Dimensions (W × H × D): 27.4 mm × 98 mm × 90 mm
- Weight: Approx. 0.15 kg
Typical Industrial Applications
The Q64DA is deployed in MELSEC-Q machine and process control systems requiring multi-channel analog output for field device command — the most common application being simultaneous speed reference commands to multiple FR-series inverter drives for coordinated multi-motor speed control from a single MELSEC-Q CPU. In automated conveyor and material handling systems with multiple variable-speed zones, the Q64DA provides independent 4–20 mA or 0–10 VDC speed references to 4 FR-A800 or FR-E700 inverter drives, enabling the MELSEC-Q sequence program to adjust each zone’s speed independently for product spacing control, accumulation management, and synchronised production line speed changes. Process control panels in water treatment, chemical processing, and food and beverage facilities use the Q64DA for PID loop output — the MELSEC-Q CPU executes PID calculations using the PID instruction, and the Q64DA converts the PID output percentage to 4–20 mA signals commanding control valves, variable speed pump drives, and proportional pressure regulators. In pharmaceutical cleanroom HVAC systems where MELSEC-Q controls supply air fan speed, exhaust fan speed, and humidification valve position simultaneously, the Q64DA provides the 4-channel capability to command all controlled variables from one module. Building automation MELSEC-Q controllers use the Q64DA for VAV (variable air volume) damper actuator positioning (0–10 VDC), chilled water valve modulation (4–20 mA), and cooling tower fan speed command (4–20 mA) — 3 of the Q64DA’s 4 channels simultaneously, with the fourth available for future expansion. Automated testing systems where the MELSEC-Q simulates sensor signals or applies reference voltages/currents to units under test use the Q64DA for calibrated signal generation under PLC program control.
Expert Tips
When using the Q64DA for PID loop output in a MELSEC-Q system, configure the Q64DA auto-refresh parameter in GX Works2 to automatically transfer the PID instruction’s output device (typically a D register holding the 0–4,095 PID output count) to the Q64DA’s channel input BFM every scan cycle — this eliminates the need for a TO instruction in the ladder program for each PID output channel and ensures the analog output updates at the same rate as the PID calculation without additional programming. For Q64DA current output channels driving long cable runs to remote field devices (cable lengths above 50 metres), verify the cable’s total loop resistance (cable resistance × 2 for the return path) plus the field device’s input impedance does not exceed the Q64DA’s 750 Ω maximum load — a 100-metre run of 0.5 mm² cable has approximately 7 Ω loop resistance, well within the 750 Ω limit for most industrial cable cross-sections. For Q64DA voltage output channels in noisy panel environments where the 0–10 VDC signal is routed near motor power cables, use shielded instrumentation cable for the analog signal wiring and connect the shield to earth at the Q64DA end only — connecting the shield at both ends creates a ground loop that can induce 50 Hz interference onto the analog signal from the earth potential difference between the two shield termination points. For MELSEC-Q systems where the Q64DA is in an extension base unit (separate from the main base unit containing the CPU), verify that the Q-series extension bus cable length between base units does not introduce significant delay in the auto-refresh data transfer — extension base auto-refresh cycles are synchronised with the Q-series internal bus scan, but very long extension bus cables (above the specified maximum length) can cause data timing issues that result in stale values appearing on the Q64DA output channels.
Frequently Asked Questions
Q: Can the Q64DA operate as an analog output module simultaneously while the Q64AD (analog input module) is reading process values in the same MELSEC-Q system?
A: Yes. The Q64DA (analog output) and Q64AD (analog input) are independent modules operating concurrently in the same Q-series base unit — both modules access the Q-series internal bus independently, and both auto-refresh parameters operate simultaneously without conflict. A typical closed-loop control configuration uses Q64AD analog inputs for process variable measurement and Q64DA analog outputs for control output commands, with the MELSEC-Q CPU executing PID calculations each scan cycle using the Q64AD measured values to update the Q64DA output setpoints.
Q: What is the Q64DA’s output response time when the CPU program changes the output setpoint via auto-refresh?
A: The Q64DA updates each analog output channel within approximately 1 ms of receiving the new digital value from the auto-refresh transfer — the total end-to-end latency from the PLC program writing the new setpoint to the analog output changing is the CPU scan time plus the auto-refresh transfer time plus the Q64DA’s 1 ms conversion time. For a Q02UCPU with a 2 ms scan time, the total latency is approximately 3–4 ms — adequate for all but the fastest closed-loop control requirements. For control loops requiring faster analog output update, the Q64DA’s output can be updated via a direct TO instruction within a timer interrupt routine executing faster than the normal scan cycle.
Q: Can the Q64DA’s channel output type be changed during PLC operation (switching between voltage and current output on a channel while the PLC is running)?
A: Yes, but with caution. The Q64DA’s channel output type can be changed during PLC operation by writing the new output type code to the channel’s configuration BFM via a TO instruction while the CPU is in RUN mode. When the output type changes, the channel output transitions immediately to the new output type — this transition should only be performed when the connected field device is not in active control, as the output value change during type switching may cause an unwanted command step to the connected actuator or drive.
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