GE DS3820CI2A

Key Parameters

• Channels: 2 independent counter/encoder inputs

• Input Type: 24 V DC (sourcing/sinking configurable)

• Maximum Input Frequency: 100 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, rate-of-change

• Input Filtering: Software-selectable 0.1–10 ms debounce (programmable per channel)

• Quadrature Decoding: Supports A/B/Z signals with index/reset input

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

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

• Power: 24 V DC backplane power, ≤2.5 W (plus external field supply)

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

• Terminals: Screw-type (suffix-dependent)

Advantages

• Dual high-speed counters – two independent 100 kHz channels in one slot; saves rack space and cost.

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

• Quadrature x4 decoding – delivers 4× resolution from standard incremental encoders (e.g., 1000 PPR becomes 4000 counts/rev).

• Index/Z-input support – allows homing and position reset for absolute referencing.

• Adjustable input filtering – eliminates false counts from contact bounce and electrical noise.

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

• 32-bit counter range – eliminates rollover concerns for most industrial applications (>4 billion counts).

• Built-in diagnostics – detects input shorts, count loss, and over-range conditions.

Applications

• Position feedback – reading incremental encoders on servo motors, conveyors, and positioning tables

• Flow measurement – counting pulses from turbine flowmeters for totalization and rate calculation

• Speed monitoring – frequency measurement from proximity sensors on rotating shafts

• Web handling – tension control and registration with encoder feedback for length measurement

• Packaging machinery – product counting and cut-to-length positioning

• Printing presses – registration control with quadrature encoders

• Conveyor systems – part counting and speed monitoring

Competitor Comparison

The DS3820CI2A offers exceptional value with two high-speed channels per slot – effectively half the cost per channel of single-counter modules. Compared to competitor 2-channel modules, the DS3820CI2A provides superior quadrature x4 decoding (higher resolution), a wider range of measurement modes (including pulse-width and period), and 32-bit resolution. Against standard counter modules that only support counting, the DS3820CI2A adds frequency and period measurement capabilities, making it a more versatile instrument for motion and flow applications. The DS3820CI2A is the go-to choice for new installations requiring multiple encoder inputs without sacrificing rack space or budget.

Selection Tips

• Choose DS3820CI2A when you need to interface with incremental encoders, flowmeters, or high-speed pulse sensors.

• Ideal for positioning, speed monitoring, flow totalization, and part counting applications.

• Verify encoder output type (sourcing/sinking) and voltage level (24 V DC) – the DS3820CI2A does not support 5 V or 12 V encoders without external level shifting.

• Consider quadrature x4 mode for maximum position resolution – especially useful for precision positioning.

• Not suitable for absolute encoders (SSI, BiSS, EnDat) – use dedicated absolute encoder modules.

• Ensure your PLC scan rate can handle the data update frequency from the DS3820CI2A (up to 100 kHz).

Precautions

• Frequency limits: The maximum 100 kHz input is achieved only with filtering disabled. Enable filtering only if necessary, as it reduces maximum frequency.

• Wiring: Use shielded twisted-pair cables for encoder signals, especially at high frequencies. Ground shield at module end only.

• Input voltage: Do not exceed 24 V DC nominal – the DS3820CI2A is not rated for higher voltages.

• Shielding: For quadrature encoders, use individually shielded pairs for A, B, and Z signals to maintain signal integrity at high speeds.

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

• Count loss: At frequencies near 100 kHz, ensure the PLC reading cycle is faster than the counter update to avoid missing counts.

• Configuration: Set the count mode (up/down, quadrature, frequency) and filter settings before enabling the channel – changing modes during operation may cause count discontinuity.

• Spare: Keep one spare DS3820CI2A for critical motion or flow loops – encoder modules are subject to field wiring faults and can be a common failure point.