GE DS3820DPAA

Key Parameters

• Channels: 8 digital inputs

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

• Input Current: 4–8 mA per channel

• Input Impedance: >5 kΩ

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

• On-state Threshold: ≥15 V DC

• Off-state Threshold: ≤5 V DC

• Minimum Detectable Pulse Width: 1 ms (captures very short pulses)

• COS Latching: Per-channel latch – holds state change until manually or automatically reset (software-configurable)

• Diagnostics: Per-channel LED status, input short-circuit protection

• Input Filtering: Software-selectable 0.5–50 ms debounce

• Power: 24 V DC backplane power, ≤2 W (plus external field supply)

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

Advantages

• Pulse-capture capability – detects pulses as short as 1 ms; standard modules typically miss pulses shorter than the PLC scan cycle.

• COS latching output – holds state changes until reset; ideal for first-fault indication and persistent alarm annunciation.

• Change-of-State (COS) detection – captures every state transition; reduces PLC CPU load by only reporting changes.

• Per-channel filtering – independently configurable 0.5–50 ms debounce; eliminates false triggers from contact bounce.

• Optical isolation – protects backplane from field transients and ground loops.

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

• High channel density – 8 channels in a single slot; saves rack space.

• Compact and cost-effective – focuses on pulse capture and latching without the complexity of full SOE time-stamping.

Applications

• Fault diagnostics – capturing momentary alarm contacts (e.g., over-temperature trips, pressure spikes) that may be too short for standard inputs

• First-fault detection – capturing the first event in a cascade of alarms (e.g., motor tripping due to high temperature)

• Pushbutton monitoring – detecting brief operator pushbutton presses for start/stop commands

• Emergency stop (E-stop) monitoring – capturing momentary E-stop activations for safety logging

• Conveyor systems – detecting brief product jams or photoeye interruptions

• Packaging machinery – capturing short-duration sensor pulses for cycle monitoring

• Manufacturing – machine cycle monitoring with event sequencing and persistent fault annunciation

Competitor Comparison

The DS3820DPAA is the pulse-capture/latching variant of the digital input family. Compared to standard digital input modules, it adds the ability to capture very short pulses (1 ms) and latching outputs – critical for applications where momentary events would otherwise be missed. Against the full-featured DS3820DIMA SOE module, the DS3820DPAA offers a lower-cost solution for applications requiring pulse detection and latching but not full time-stamped event logging. For diagnostic and first-fault applications, the DS3820DPAA delivers essential functionality without unnecessary cost.

Selection Tips

• Choose DS3820DPAA when you need to capture short-duration pulses (≥1 ms) that standard modules would miss.

• Ideal for fault diagnostics, momentary alarm detection, and first-fault indication.

• Verify the input voltage matches your field devices – accepts 24 V DC only.

• Consider the latching reset method – software reset (via PLC) or manual reset – configurable per channel.

• Not suitable for AC input signals – use the DS3820C12A family for 120 V AC inputs.

• If you also require time-stamping and event logging, consider the DS3820DIMA SOE module instead.

• Ensure your PLC/DCS can receive and process latch reset commands.

Precautions

• Pulse duration: The DS3820DPAA captures pulses ≥1 ms with filtering disabled. Enabling filtering will increase the minimum detectable pulse width – match to your application requirements.

• Latching behavior: The latch holds the state change until reset. Configure the reset mechanism carefully – automatic reset may clear alarms before operator acknowledgment; manual reset ensures operator visibility.

• Filtering: Longer filter settings (50 ms) improve noise immunity but may miss short pulses – use minimal filtering for pulse-capture applications.

• Wiring: Use shielded cables for inputs in high-EMI areas.

• Power sequencing: Apply backplane power before field power to avoid false events during startup.

• No event buffer: The DS3820DPAA does not store historical events – the latch provides current status only. For event logging, consider SOE modules.

• Spare: Keep one spare DS3820DPAA for critical pulse-capture applications – the unique feature set may have longer lead times.