Schneider AS‑BDAU‑204 4‑Channel Analog Output Module

The Schneider AS‑BDAU‑204 belongs to the Modicon Compact series. It is a 4‑channel analog output module for Modicon 984 / A20 Compact PLC systems, converting digital commands into configurable 4‑20mA or 0‑10V analog control signals for field regulating actuators.

This rack‑mounted I/O module features 12‑bit resolution, open‑loop wire break detection and status LED indicators. Original production has been discontinued. It is widely supplied as aftermarket spare parts for legacy water treatment, HVAC and manufacturing automation retrofits and maintenance.

Main Specifications

• Brand:Schneider Modicon; Model:AS‑BDAU‑204; Type:4‑Channel Analog Output Module
• Output Ranges:Independently configurable 4‑20mA current or 0‑10V DC voltage per channel
• Resolution:12‑bit, built‑in wire break diagnosis for current loop wiring faults
• Power Supply:24VDC external power, plug‑in rack installation with backplane bus communication
• Status Indicators:Module ready LED, channel activity LED and fault warning LED on front panel
• Compatibility:Designed for Modicon 984 and A20 Compact PLC automation racks
• Supply Status:Original production discontinued, available as tested surplus or refurbished spare parts

Core Functions

• Receive digital control instructions from PLC CPU via rack backplane and convert to continuous analog signals.
• Drive modulating valves, dampers and variable‑speed drives to realize closed‑loop process regulation.
• Detect broken current loop wiring and send fault alarms to the PLC for maintenance alerts.
• Hold the last output value upon CPU communication loss to avoid sudden process disturbance.
• Each channel can be individually set to voltage or current mode to fit different field devices.
• Serve as analog control interface of legacy Modicon Compact PLC automation systems.

Application Scenarios

• Process control of waterworks, sewage treatment plants, HVAC systems and packaging machinery.
• Spare I/O module replacement and routine maintenance of existing Modicon Compact PLC racks.
• Technical renovation and stable control upgrade of aging factory automation control cabinets.
• On‑site troubleshooting and replacement of faulty analog output modules on running production lines.
• Spare‑parts stocking for system integrators and industrial automation maintenance contractors.
• Global aftermarket spare supply for technicians maintaining obsolete Schneider Modicon legacy hardware.

FAQ

• Q:What is the difference between AS‑BDAU‑204 and AS‑DAU‑204?
  A:They are functionally identical; the prefix B denotes a later hardware revision version.
• Q:Does it support wire break detection?
  A:Yes, it can identify open circuits on 4‑20mA loops and trigger fault status feedback.

• Q:Is this analog output module still in original production?
  A:Schneider has stopped manufacturing this model, only tested surplus and refurbished spare units are available.