The QX41 is Mitsubishi Electric’s 16-point 24 VDC sink digital input module for the MELSEC-Q programmable controller series with screw terminal field wiring — providing 16 optically isolated 24 VDC sink (NPN-compatible) input points with a 18-terminal screw terminal block for direct field wire connection, the standard 16-point sink input module for MELSEC-Q systems where screw terminal wiring convenience is preferred over the 40-pin connector of the higher-density QX80 module. Atlantech Drives holds stock of the QX41. Contact us for fast worldwide delivery and competitive pricing.
What Is the QX41?
The QX41 is a MELSEC-Q series digital input module providing 16 individually optically isolated 24 VDC sink input points with an 18-terminal screw terminal block (16 input terminals plus 2 common terminals) for direct field wiring without connector assembly or terminal block adapters. The module installs in any I/O slot in a Q-series main or extension base unit, with 16 input addresses automatically assigned based on slot position. Each input point accepts 24 VDC signals from NPN-output proximity sensors, photoelectric sensors, limit switches, and push buttons — the standard 24 VDC sink input compatible with the majority of industrial sensor outputs in European and international machine specifications. The QX41’s screw terminal block accepts conductors of 0.3–0.75 mm² cross-section directly — no crimped ferrule, no connector assembly, no special tooling required for field wiring, making the QX41 the preferred module for field-wired installations where wiring simplicity and maintenance accessibility are priorities. Compared to the QX80 (32-point, 40-pin connector), the QX41 provides half the input point density per slot in exchange for significantly simpler field wiring — the correct trade-off when slot count is not the primary constraint and ease of field wiring and individual wire tracing during fault finding is valued over maximum input density.
Key Technical Specifications
- Model: QX41
- Input Points: 16
- Input Type: 24 VDC sink (NPN-compatible)
- Input Voltage Range: 20.4–28.8 VDC (signal ON), ≤6 VDC (signal OFF)
- Input Current: 4 mA typical at 24 VDC
- Response Time: 10 ms standard (adjustable 1–70 ms via parameter)
- Isolation: Optical, per input point
- Common Configuration: 16 points per common (shared — 2 common terminals)
- Field Wiring: 18-terminal screw terminal block (direct wire termination)
- Power Consumption: 5 VDC internal bus, approx. 0.09 A
- Operating Temperature: 0°C to 55°C
- Dimensions (W × H × D): 27.4 mm × 98 mm × 89.3 mm
- Weight: Approx. 0.12 kg
Compatibility & System Integration
The QX41 is compatible with all MELSEC-Q main base units (Q3□B, Q5□B, Q6□B, Q3DB) and extension base units — installation in any available I/O slot provides automatic 16-point input address assignment by the Q-series CPU’s I/O scan. In MELSEC-Q systems with mixed input requirements (some inputs requiring high density from QX80 and others benefiting from QX41’s screw terminal wiring), both module types can coexist in the same base unit in different slots — the system assigns input addresses sequentially across all input modules regardless of module type. The QX41’s 1 ms minimum response time (configurable via GX Works2 I/O module parameters) is the same as the QX80, enabling both modules to be used for applications requiring fast input response. For MELSEC-Q systems requiring PNP (source) input compatibility instead of the QX41’s NPN (sink) input, the QX41-S1 (source input variant) provides the same 16-point screw terminal architecture with source input circuits — verify the sensor output type (NPN sink or PNP source) before selecting between QX41 and QX41-S1. The QX41 is also compatible with field wiring via the optional terminal block relay adapter (A6RLY series) for MELSEC-Q systems requiring relay isolation between the PLC input and field sensor wiring, enabling the screw terminal’s simple wiring approach to be extended to relay-isolated input architectures without connector assembly hardware.
Maintenance Tips
The QX41’s screw terminal field wiring is the primary maintenance point — inspect screw terminal tightness annually using a calibrated torque screwdriver at the specified terminal tightening torque (typically 0.5–0.6 N·m for M3 screw terminals) — under-torqued terminals cause increased contact resistance and eventually intermittent input signal failures that are difficult to diagnose without physical terminal inspection. For installations in high-vibration environments (press rooms, stamping lines, near large pump or compressor machinery), reduce the terminal inspection interval to every 6 months — vibration progressively loosens screw terminals even when initially tightened to specification. For QX41 modules above 10 years of service, inspect the terminal block insert for conductor insulation discolouration (brown or black staining around the conductor entry point indicates sustained elevated temperature from a high-resistance connection) — replace the terminal block insert if discolouration is visible, as the discolouration indicates the terminal’s contact resistance has increased sufficiently to generate heat, which progressively degrades the terminal insert’s thermoplastic material. When replacing conductors connected to a QX41 (during panel rewiring or conductor fatigue replacement), use the correct conductor cross-section (0.3–0.75 mm²) and strip the conductor to the correct length — over-stripped conductors with exposed conductor extending beyond the terminal housing create short-circuit risk to adjacent terminals in the 18-terminal screw block’s compact pitch.
Frequently Asked Questions
Q: Can the QX41’s response time be reduced below 10 ms for specific critical inputs without affecting other inputs on the same module?
A: Yes. The QX41’s response time can be adjusted per input point group via the I/O module parameter settings in GX Works2 — the minimum response time of 1 ms can be set for specific input points while other points on the same module retain the default 10 ms or a different configured value. Reducing response time increases the module’s susceptibility to input noise — only reduce response time below 5 ms for inputs with well-filtered, noise-free signal sources, and verify that sensor output signals meet the minimum ON voltage (>20.4 VDC) and minimum source current (>4 mA) specifications reliably before reducing the response time.
Q: What is the maximum number of QX41 modules that can be installed in a single MELSEC-Q base unit?
A: The maximum number of QX41 modules per base unit is limited by available I/O slots — a Q38B provides 6 I/O module slots (supporting up to 6 QX41 modules for 96 input points from one base unit), a Q312B provides 10 I/O module slots (up to 10 QX41 modules for 160 input points). Extension base units (Q6□B) provide additional slots for further QX41 modules. The MELSEC-Q system’s total I/O limit of 4,096 points applies to the combined input and output count across all modules in all base units.
Q: Is the QX41 compatible with MELSEC iQ-R base units, or only with MELSEC-Q base units?
A: The QX41 uses the Q-series internal bus interface — it is compatible only with MELSEC-Q base units (Q3□B, Q5□B, Q6□B, Q3DB, Q6□B extension bases). MELSEC iQ-R base units use a different R-series bus interface that is physically and electrically incompatible with Q-series modules including the QX41. For MELSEC iQ-R systems, the equivalent module is the RX40C5 or RX40C6 16-point digital input module for the R-series base unit.
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