GE DS3820CI2BH21B1A

Key Parameters

• Channels: 2 independent counter/encoder inputs

• Input Type: 5 V differential (RS-422) – compatible with A+, A-, B+, B-, Z+, Z-

• Maximum Input Frequency: 500 kHz per channel (with filter disabled)

• Resolution: 32-bit counter per channel

• Count Modes: Up/down counting, quadrature x1/x2/x4, frequency measurement, period measurement, pulse-width measurement

• Input Filtering: Software-selectable 0.1–10 ms debounce (reduces max frequency when enabled)

• Auxiliary Power Output: Isolated 5 V DC, 200 mA – for powering encoders directly from module

• Isolation: 1500 V RMS (field-to-backplane); 500 V RMS between channels; 1500 V RMS for auxiliary output

• Terminal Type: 21-pin screw-type (per suffix “H21B”)

• Diagnostics: Per-channel LED status, over-range detection, count-lost detection, auxiliary output short-circuit protection

• Power: 24 V DC backplane power, ≤4 W (including auxiliary output load)

• Operating Temperature: –40°C to +70°C

Advantages

• High-speed 500 kHz input – supports high-resolution encoders and high-speed motion applications; 5× faster than standard 24 V versions.

• Integrated 5 V auxiliary power – provides isolated 5 V DC for encoders; eliminates separate power supply.

• 5 V differential (RS-422) – standard for most precision incremental encoders; direct compatibility without level shifting.

• Quadrature x4 decoding – delivers 4× resolution from standard encoders (e.g., 5000 PPR becomes 20,000 counts/rev).

• Versatile measurement modes – counting, quadrature, frequency, period, and pulse-width all in one module.

• Hot-swappable – replace without rack power-down.

• 32-bit resolution – eliminates rollover concerns for most high-speed applications.

Applications

• Precision servo positioning – high-resolution encoder feedback for CNC machines, robotics, and pick-and-place equipment

• High-speed web handling – cut-to-length and registration control with high-PPR encoders

• Motor speed control – high-frequency pulse monitoring for VFD feedback

• Printing presses – high-speed registration and color-to-color alignment

• Semiconductor manufacturing – wafer handling and precision stage positioning

• Laboratory automation – high-resolution motion stages and positioning systems

• Packaging machinery – high-speed product counting and synchronization

Competitor Comparison

The DS3820CI2BH21B1A is the high-speed variant of the counter family, delivering 500 kHz input frequency – five times faster than standard models. Compared to the 24 V DS3820CI2AG21C1A, it sacrifices spring-clamp convenience for higher performance and adds 5 V auxiliary power specifically for RS-422 encoders. Against competitor high-speed modules, the DS3820CI2BH21B1A offers a broader range of measurement modes (frequency, period, pulse-width) and higher auxiliary power capacity (200 mA vs. 150 mA) at a more competitive price. For precision motion control and high-speed positioning, the DS3820CI2BH21B1A is the clear choice.

Selection Tips

• Choose DS3820CI2BH21B1A for high-speed precision applications – CNC, robotics, high-resolution positioning, and high-PPR encoders.

• Ideal for encoders requiring 5 V power (most incremental encoders) – the integrated auxiliary output eliminates external power supplies.

• Verify encoder frequency output does not exceed 500 kHz – the DS3820CI2BH21B1A is designed for high-speed signals.

• Confirm encoder output is RS-422 differential (5 V) – this module does not support single-ended or 24 V inputs.

• Not suitable for standard 24 V proximity sensors or low-speed counting applications.

• Consider screw-terminal wiring – the DS3820CI2BH21B1A uses screw-type terminals (not spring-clamp).

Precautions

• Auxiliary power capacity: Total current draw from the 5 V output must not exceed 200 mA – exceeding this will trip short-circuit protection.

• Frequency limits: Maximum 500 kHz achieved only with filtering disabled. Enabling filtering will reduce maximum frequency – use only if necessary.

• Differential wiring: Use twisted-pair shielded cables for each differential pair (A+/A-, B+/B-, Z+/Z-). Maintain proper cable twist to maximize noise rejection at high frequencies.

• Cable length: At 500 kHz, keep cables as short as possible (<30 m recommended). Longer cables may cause signal degradation and count errors.

• Termination: For long cables, consider adding 120 Ω termination resistors at the module end to reduce reflections.

• Grounding: Ground shield at module end only to avoid ground loops.

• Power sequencing: Apply backplane power before field power to avoid spurious counts during startup.

• Configuration: Set count mode and filter settings before enabling the channel – changing modes during operation may cause count discontinuity.

• Spare: Keep one spare DS3820CI2BH21B1A for critical motion loops – high-speed modules typically have longer lead times.