Model Interpretation

AS: Modicon Automation System

B821: 8‑point DC input module

108: 10–60VDC, 8 points, 2 points per common (vs 1 common for ‑008)

Technical Parameters

Inputs: 8 channels, 10–60VDC nominal

Logic: Sink (negative common) / Source (positive common) selectable

On Voltage: ≥10VDC; Off Voltage ≤5VDC

Input Current: ≈7mA @ 24VDC

Isolation: 1500VAC channel‑to‑backplane

Response Time: ≤10ms (ON/OFF)

Backplane Power: +5V 50mA

Operating Temp: 0°C to +60°C

Storage Temp: -40°C to +85°C

Humidity: 5%–95% non‑condensing

Weight: ≈0.3kg

Dimensions: 50×119×125mm

Origin: France

Interface & Configuration

Backplane: Modicon 800/984 I/O bus

Terminals: Screw terminals (8 inputs, 4 commons; 2 points per common)

Indicators: LED per channel (ON when input active)

Wiring: 0.5–2.5mm² copper wires

Core Functions

DC Signal Sensing: 8‑point input for 10–60VDC devices

Dual Logic: Selectable sink/source for sensor flexibility

Grouped Commons: 2 points per common reduces wiring complexity

Noise Immunity: High isolation reduces ground loops

LED Diagnostics: Quick channel status verification

Applications

Systems: Modicon 800, 984, 300‑series PLCs

Industries: Material handling, packaging, textile, general automation

Use Cases: Proximity sensors, photoelectric switches, pushbuttons, relay contacts

Compatibility

Racks: Modicon 800/984 8/11‑slot backplanes

CPUs: AS‑984B‑128, PC‑E984‑685, AS‑9370‑001

Software: Concept, ProWORX 32, P190

Status

Discontinued: Obsolete, no longer manufactured

Availability: Refurbished/used or new surplus with 1–2 year warranty