The FX2N-2HC is Mitsubishi Electric’s 2-channel high-speed counter special function module for the MELSEC FX2N compact PLC series, providing two independent channels of 50 kHz high-speed pulse counting each with a dedicated hardware comparison output — doubling the channel count of the FX2N-1HC to deliver simultaneous high-speed position measurement and hardware comparison activation on two independent encoder inputs from a single extension bus module. As the 2-channel version of the FX2N high-speed counter module range, the FX2N-2HC is specified for applications requiring two simultaneous hardware-speed counting channels — two-axis cam switching, dual-register-mark detection in 2-lane web processes, and dual-axis cut-to-length systems — where installing two FX2N-1HC modules would consume two extension bus positions. Available now at Atlantech Drives with worldwide express delivery and 12-month warranty — complete our quote form for pricing and availability.
What Is the FX2N-2HC?
The FX2N-2HC is a MELSEC FX2N series special function module providing two independent channels of high-speed pulse counting at up to 50 kHz per channel, each with its own hardware comparison output circuit activating within 0.1 ms of the counter reaching the preset comparison value. Both channels operate fully independently — each has its own encoder input terminals, comparison value registers, comparison output terminal, and latch input terminal, so channel 1 and channel 2 can count different encoder signals at different frequencies, use different counting modes (quadrature versus single-phase), and have completely independent comparison values and output timing. The dual-channel architecture of the FX2N-2HC provides the same per-channel functionality as the FX2N-1HC but in a single extension bus module — saving one FX2N extension bus position and reducing the module count compared to two separate FX2N-1HC installations. The FX2N-2HC communicates with the FX2N CPU via FROM/TO buffer memory instructions using a dedicated buffer memory map for each channel, with channel 1 and channel 2 data stored in separate buffer memory address ranges accessible via individual FROM/TO instructions in the FX2N ladder program.
Key Technical Specifications
- Model: FX2N-2HC
- Counter Channels: 2 (independent)
- Maximum Count Frequency: 50 kHz per channel
- Counter Input Types: AB quadrature (×1, ×2, ×4), single-phase up/down, CW/CCW (per channel)
- Counter Range: -2,147,483,648 to +2,147,483,647 (32-bit signed, per channel)
- Comparison Output: 1 hardware output per channel (2 total), transistor 24 VDC, within 0.1 ms
- Comparison Registers: 2 per channel (upper and lower for window detection)
- Latch Input: 1 per channel (2 total)
- Extension Bus Occupation: 8 I/O points
- External Power Supply: 24 VDC ±10%, 150 mA (required)
- Operating Temperature: 0°C to 55°C
- Compatible FX2N base units: All FX2N models
- Weight: Approx. 0.18 kg
Typical Industrial Applications
The FX2N-2HC is deployed in applications where two simultaneous hardware-speed counting channels are required from a single FX2N extension bus module. In dual-lane packaging systems where two parallel conveyor lanes carry product simultaneously, the FX2N-2HC monitors the position of both lanes independently via two encoder inputs — the channel 1 comparison output triggers the first lane’s cut or divert actuator at the precise position for lane 1, and the channel 2 comparison output independently triggers lane 2’s actuator at its preset position, with both outputs responding within 0.1 ms of the respective count threshold regardless of the FX2N CPU scan time. In two-axis CNC engraving and routing machines using FX2N-10PG for axis drive, the FX2N-2HC provides secondary load-side position verification — channel 1 monitors an X-axis linear encoder and channel 2 monitors a Y-axis linear encoder, with both channels’ current values read by the FX2N program via FROM instructions to compare against the FX2N-10PG’s commanded positions and detect mechanical slip or compliance errors. Label printing machines with two print heads processing two web lanes simultaneously use the FX2N-2HC for dual-lane registration mark detection — channel 1 captures the registration mark position on lane 1 via the latch input and comparison output, while channel 2 independently manages lane 2 registration, enabling independent phase correction for each lane without the print head timing for one lane affecting the other. In multi-spindle machining centres, the FX2N-2HC monitors two spindle encoder signals simultaneously for synchronised speed control, with each channel’s counter value read by the FX2N program to calculate the speed error for individual spindle correction.
Replacement & Upgrade Notes
The FX2N-2HC is a discontinued Mitsubishi product available for maintenance replacement through specialist distributors. For FX2N installations where the FX2N-2HC has failed and a direct replacement cannot be sourced, two FX2N-1HC modules provide equivalent functionality at the cost of an additional extension bus position — verify the FX2N system has a free extension bus slot before adopting this alternative. The ladder program’s FROM/TO instruction addresses must be updated to reference the two separate module numbers when replacing one FX2N-2HC with two FX2N-1HC modules. For FX3U-based system upgrades replacing FX2N-2HC functionality, the MELSEC-Q QD62E high-speed counter module provides 2-channel 500 kHz counting with hardware comparison output — 10× the 50 kHz frequency capability of the FX2N-2HC — for installations where higher measurement frequency improves process performance. For FX3U-platform replacements retaining the compact PLC form factor, multiple FX3U-PHSC-ADP high-speed counter adapters (if available) or the FX3U base unit’s 6 built-in high-speed counter inputs (which support software comparison via the DHSZ instruction, though without the FX2N-2HC’s hardware output response speed) provide alternative counting architectures. When migrating FROM/TO-based FX2N-2HC programs to GX Works2 for FX3U, note that the FX2N-2HC buffer memory map address structure does not directly translate to FX3U module addressing — consult Mitsubishi’s FX2N-to-FX3U migration documentation for counter module buffer memory remap guidance.
Frequently Asked Questions
Q: Can the FX2N-2HC’s two channels be configured for different counting modes simultaneously?
A: Yes. Channel 1 and channel 2 of the FX2N-2HC have independent counting mode configuration registers — channel 1 can be configured for AB quadrature ×4 mode while channel 2 uses single-phase up/down mode, or any other combination of supported counting modes. Configure each channel’s mode via TO writes to the respective channel mode registers (BFM#1 for channel 1, BFM#17 for channel 2) at power-up initialisation in the FX2N program’s M8002 (first-scan) ladder section.
Q: Is the FX2N-2HC’s external 24 VDC power requirement higher than the FX2N-1HC due to the additional channel?
A: Yes. The FX2N-2HC requires 150 mA at 24 VDC versus 100 mA for the FX2N-1HC — the additional 50 mA reflects the power consumption of the second counter channel and comparison output circuit. For installations where the external 24 VDC supply is shared between multiple FX2N special function modules, verify that the total current demand of all modules does not exceed the supply’s rated capacity, accounting for the FX2N-2HC’s 150 mA requirement alongside the FX2N-4AD’s 55 mA, FX2N-4DA’s 120 mA, and any other modules on the same supply rail.
Q: Can the FX2N-2HC’s latch inputs on both channels be used simultaneously to capture two independent events at the same time?
A: Yes. Each channel’s latch input operates independently and simultaneously — a rising edge on channel 1’s latch input captures channel 1’s current counter value into channel 1’s latch register, while a simultaneous rising edge on channel 2’s latch input captures channel 2’s counter value into channel 2’s latch register. Both latch captures occur in hardware within the FX2N-2HC module without CPU involvement, providing synchronised dual-channel position capture from two independent events that occur at the same moment or within microseconds of each other — a capability not achievable with software-based position capture using the FX2N CPU program.
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