The FX2N-4DA is Mitsubishi Electric’s 4-channel analogue output special function module for the MELSEC FX2N compact PLC series, providing four independent channels of 12-bit digital-to-analogue conversion with software-configurable output ranges — the most widely installed analogue output module in the FX2N platform, serving as the standard output partner to the FX2N-4AD in closed-loop process control installations involving variable frequency drives, proportional valves, analogue setpoint controllers, and multi-axis analogue-commanded positioning systems. Unlike the FX2N-2DA’s hardware rotary switch range selection, the FX2N-4DA configures each channel’s output range via buffer memory TO writes from the FX2N program, enabling remote range changes and multi-range channel mixing without physical module access. Atlantech Drives holds stock of the FX2N-4DA. Contact us for fast worldwide delivery and competitive pricing.
What Is the FX2N-4DA?
The FX2N-4DA is a MELSEC FX2N series special function module providing four channels of 12-bit digital-to-analogue conversion with software-configurable output ranges. The module installs in the FX2N extension bus and communicates with the FX2N CPU via TO buffer memory write instructions — channel output values and range configuration are both written via TO instructions, with the range configuration written at power-up initialisation and the output values updated each scan cycle. Four independent output channels enable multi-variable closed-loop control from a single module: simultaneous speed reference to a variable frequency drive (0–10 VDC), flow setpoint to a proportional control valve (4–20 mA), pressure setpoint to a pressure regulator (4–20 mA), and temperature setpoint to an external controller (0–10 VDC), all from one FX2N-4DA module. Each channel is independently configurable for voltage output (0–5 VDC, 0–10 VDC, -10 to +10 VDC) or current output (4–20 mA, 0–20 mA) via dedicated range setting registers in buffer memory, enabling different output types on different channels simultaneously without hardware modification. The 12-bit resolution provides 4,096 discrete output levels per channel with ±1% full-scale accuracy at 25°C.
Key Technical Specifications
- Model: FX2N-4DA
- Analogue Output Channels: 4
- Resolution: 12-bit (4,095 output levels per channel)
- Output Range (Voltage): 0–5 VDC, 0–10 VDC, -10 to +10 VDC (software configurable per channel)
- Output Range (Current): 4–20 mA, 0–20 mA (software configurable per channel)
- Maximum Output Current (Voltage Mode): 10 mA per channel
- Load Resistance (Current Mode): 600 Ω maximum
- Output Accuracy: ±1% of full scale at 25°C
- Output Response Time: 4 ms (all 4 channels updated simultaneously)
- Extension Bus Occupation: 8 I/O points
- External Power Supply: 24 VDC ±10%, 120 mA (required)
- Operating Temperature: 0°C to 55°C
- Compatible FX2N base units: All FX2N models
- Weight: Approx. 0.18 kg
Compatibility & System Integration
The FX2N-4DA is the standard analogue output module for FX2N-based closed-loop process control systems and is designed to work in direct combination with the FX2N-4AD analogue input module — the FX2N-4AD measures the process variable and the FX2N-4DA outputs the manipulated variable, with the FX2N PID instruction (PID) or custom control algorithm in the FX2N ladder program completing the closed-loop. This FX2N-4AD + PID + FX2N-4DA architecture is the dominant closed-loop control configuration in thousands of active FX2N installations and represents the primary maintenance replacement scenario for the FX2N-4DA. The FX2N-4DA’s four output channels can serve four simultaneous independent control loops — four PID temperature controllers each with their own process variable from FX2N-4AD channels and their own manipulated variable output from FX2N-4DA channels, providing complete four-zone temperature control from two modules and the FX2N base unit. The FX2N-4DA is also used in feed-forward and cascade control architectures where multiple analogue setpoints must be generated simultaneously at different rates — the four independent channels with simultaneous 4 ms update ensures all setpoint outputs change in the same scan cycle, maintaining the intended setpoint ratio relationships without inter-channel timing errors. For Mitsubishi variable frequency drive (FR-series) speed control, the FX2N-4DA’s 0–10 VDC output connects directly to the FR drive’s frequency setting input (terminal 2) — the FX2N-4DA is the standard solution for analogue frequency reference generation in FX2N + FR-series drive installations where the drive cannot be controlled via RS-485 communication.
Troubleshooting Guide
If the FX2N-4DA outputs are not responding to TO write instructions, verify first that the external 24 VDC power supply is connected and within range — the FX2N-4DA requires 24 VDC at 120 mA for the analogue output circuit, and a missing external supply causes all outputs to remain at zero regardless of the digital value written to buffer memory. Confirm power supply presence using GX Works2’s special function module monitor — if the module status register (BFM#29) shows an error flag, the most common cause is missing or out-of-range external supply. For individual channels producing incorrect output levels despite correct digital values written to buffer memory, verify the channel range configuration register (BFM#16–19) contains the correct range code — if the range register has been unintentionally overwritten with an incorrect value, the DAC output will scale incorrectly for the connected load. Read the range registers using FROM instructions in GX Works2’s device monitor and verify each channel’s range code matches the intended output type. For current output channels producing less than 20 mA at full scale despite correct digital values, check the total loop resistance — measure the total resistance between the FX2N-4DA current output terminal and the 0 V return terminal including all cables and the load input resistance, and verify the total is below 600 Ω. For voltage output channels with significant offset error (non-zero output when the digital value is 0), the FX2N-4DA’s gain and offset trim registers can compensate for this — BFM#20–27 provide individual gain and offset adjustment per channel, accessible via TO instructions from GX Works2 or from the FX2N calibration program.
Frequently Asked Questions
Q: Can the FX2N-4DA generate a bipolar ±10 VDC output for applications requiring both positive and negative voltage setpoints?
A: Yes. The FX2N-4DA supports -10 to +10 VDC bipolar voltage output on any channel — configure the channel range register (BFM#16 for channel 1, etc.) with the bipolar range code via a TO instruction. In bipolar mode, the digital value range is -2048 to +2047 (signed 12-bit integer), with 0 corresponding to 0 VDC output, -2048 corresponding to -10 VDC, and +2047 corresponding to +10 VDC. This bipolar output is used for position reference signals to servo drives requiring ±10 VDC velocity or torque commands.
Q: What is the maximum number of FX2N-4DA modules that can be installed in a single FX2N system?
A: The FX2N-4DA occupies 8 I/O points in the FX2N extension bus address space. With the FX2N’s 256-point maximum total I/O and 8 points per module, a theoretical maximum of 32 special function modules could be installed — but in practice, the FX2N extension bus supports a maximum of 8 special function modules (not I/O expansion units). Each special function module is assigned a module number from 0 to 7, and FROM/TO instructions reference the module by this number. For systems requiring more than 4 × 4 = 16 analogue output channels, multiple FX2N-4DA modules can occupy multiple of the 8 available positions alongside other special function modules.
Q: If the FX2N program does not execute a TO write to the FX2N-4DA in a scan cycle (for example, during CPU STOP mode), what happens to the analogue outputs?
A: The FX2N-4DA holds its last commanded output value when the FX2N CPU enters STOP mode or when TO writes are not executed in consecutive scan cycles — the module does not automatically clear its outputs on CPU STOP unless explicitly configured to do so via the output hold/clear setting in BFM#28. This hold behaviour is appropriate for some applications (maintaining a valve position during a CPU mode change) but potentially unsafe for others (a heating control output maintaining maximum power during CPU STOP). Configure BFM#28 to clear outputs (set to 0 V or 4 mA) on CPU STOP for heating, pressure, and other applications where maintaining maximum output during a PLC fault is a safety concern.
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