Key Technical Specifications
| Parameter | Value |
|---|---|
| Manufacturer | Schneider Electric / Modicon |
| Part Number | AS-BDAO-216 |
| Product Type | 16-point discrete output module |
| Output Technology | Electromechanical relay, Form A (N.O.) contacts |
| Channel Count | 16 isolated outputs |
| Switching Voltage | 120/240 VAC or 24 VDC (verify per OEM datasheet) |
| Current per Point | 2 A resistive (typical) |
| Isolation | Channel-to-channel and channel-to-logic isolation via relay contacts |
| Indicators | Per-channel LED status indicators |
| Mounting | Modicon 800 Series I/O rack |
| Operating Temperature | 0 to 60 °C (verify with OEM datasheet) |
| Protection Class | IP20 (panel-mounted rack installation) |
| Hot-Swap Support | Not supported |
Product Introduction
Relay output modules do not fail gracefully. They fail when a contact welds shut at 2 AM, when a solenoid bank draws more inrush than the nameplate suggested, or when someone assumes “2 amps per point” means “2 amps forever on all 16 points simultaneously.” The AS-BDAO-216 has been sitting in Modicon 800 racks for decades doing exactly one thing: taking a bit from the PLC logic and closing a physical contact. No PWM. No fancy diagnostics. Just metal touching metal.That is also why engineers still hunt for replacements. This module belongs to the Modicon 800 series, a legacy platform that predates most modern PAC architectures. It provides 16 relay outputs capable of switching 120/240 VAC or 24 VDC loads directly, which eliminates the need for external interposing relays in many applications. The isolation between channels means a ground fault on one output does not necessarily take down the entire module. But relay life is finite. Contact erosion, coil fatigue, and mechanical wear are real. If your module has been cycling a compressor starter ten thousand times a day, do not be surprised when it finally gives up.
Quality SOP & Tech Pitfalls
The Lab Report (SOP)Every unit goes through the same pre-shipment protocol:
- Visual and counterfeit inspection — part number, revision label, connector pins, PCB discoloration, relay housing integrity, and terminal block condition.
- Continuity and insulation checks — multimeter verification of each relay contact path and isolation boundaries (Fluke 115 or equivalent).
- Live bench test — installed in a Modicon 800 test rack; each output energized and verified for contact closure, LED indication, and proper de-energization.
- Coil resistance check — relay coil resistance measured per channel to detect early-stage coil degradation.
- Final packaging — anti-static bag, revision label, and test record included.
The Engineer’s Warning (Pitfalls)Two mistakes destroy this module faster than anything else.First, exceeding the group current rating. Yes, each point is rated for 2 A. No, you cannot run all 16 points at 2 A simultaneously. The internal bus and common terminals have a lower group limit. I have seen a tech wire sixteen 24 VDC solenoids directly to one module, wonder why the terminal block melted, and then blame Schneider. The datasheet tells you the group limit. Read it.Second, switching inductive loads without flyback suppression. Relay contacts hate inductors. A solenoid or relay coil dumped directly across those contacts will arc every time it opens. Over time, the contacts pit, weld, or stick. Add a snubber for AC loads or a flyback diode for DC loads. It costs three dollars and saves a three-thousand-dollar downtime event.
Installation & Configuration Guide
1. Pre-Installation
- Notify operations and place all controlled outputs in a safe state.
- De-energize the PLC rack and field power supplies.
- Photograph all terminal wiring, channel assignments, and module position in the rack.
- Verify the replacement part number reads AS-BDAO-216.
2. Removal
- Label each field wire by channel number and common terminal.
- Release the module retaining clips or mounting hardware.
- Withdraw the module carefully from the rack. Do not yank the ribbon cable if present.
3. Installation
- Confirm the new module matches the original revision and slot position.
- Seat the module firmly into the rack until the retaining clips engage.
- Reconnect field wiring exactly as labeled. Verify common terminals match the original configuration.
- Torque terminal screws to the manufacturer recommendation.
4. Power-On & Testing
- Restore rack power first, then field power.
- Verify LED indicators correspond to the expected output states.
- Force each output from the PLC program one at a time and verify field device response.
- Check for stuck contacts, unexpected closures, or overheating terminals before returning to normal service.
Compatible Replacement Models
- ✅ AS-BDAO-216 — Direct replacement for the same Modicon 800 series 16-point relay output module. Verify revision suffix before installation.
- ⚠️ Other Modicon 800 DO modules (e.g., AS-BDAO-xxx variants) — May share the same rack form factor but differ in channel count, voltage rating, or output type (relay vs. triac vs. transistor). Treat as non-equivalent unless the OEM documentation confirms interchangeability.
- ❌ Modicon Quantum (140 series) or Modicon X80 modules — Different rack, different backplane, different wiring. Not a drop-in replacement. A full rack and I/O migration would be required.
Frequently Asked Questions (FAQ)
Can I hot-swap the AS-BDAO-216?
No. The Modicon 800 series does not support hot swap for I/O modules. De-energize the rack before removal.Is this module AC or DC?
Both. The relay contacts can switch 120/240 VAC or 24 VDC loads. That is the advantage of relay outputs — they are voltage-agnostic up to their rated limits.Can I use this on a Modicon Quantum or M340 rack?
No. The AS-BDAO-216 fits only the Modicon 800 series I/O rack. Quantum, M340, and X80 platforms use completely different mechanical and electrical interfaces.What is the most common failure mode?
Welded or pitted relay contacts from switching inductive loads without suppression. Second most common: exceeding the group current rating and overheating the terminal block.How do I know if my load is too much for this module?
Check the per-point current rating, the group current limit, and the inrush current of your load. If you are switching solenoids, contactors, or incandescent lamps, assume the inrush is 5–10× the steady-state current. Add interposing relays if needed.Is this an original Schneider part?
We supply new surplus and tested surplus material. Exact origin, revision, and test records are provided per unit. If you require factory-sealed stock, request it before ordering.Can I substitute a transistor output module instead?
Not without verifying voltage, current, and wiring compatibility. Transistor outputs are DC-only and have different leakage, voltage drop, and protection characteristics. Do not swap output technologies without reviewing the field wiring and load type.
