Siemens Implementation

AS-Interface for Siemens

Actuator Sensor Interface - simple, low-cost fieldbus for binary sensors and actuators at the lowest automation level.

Type: FieldbusSpeed: 167 kbps (v3), 1.67 Mbps (v5)Released: 1994Organization: AS-International Association

1.67 Mbps (AS-i 5)

Bandwidth

62 (v3), 32 (v5 with 4 modules each)

Max Nodes

100m (300m with repeaters)

Max Distance

Yes

Real-Time

Protocol Overview

Actuator Sensor Interface - simple, low-cost fieldbus for binary sensors and actuators at the lowest automation level.

When to Use AS-Interface

Choose AS-Interface for simple binary I/O networks, cost-sensitive applications, or connecting many simple sensors/actuators.

Technical Specifications

Physical Layer

Physical Layer: Proprietary 2-wire
Cable Type: Unshielded 2-wire cable
Topology: Tree, Star, Ring
Power Over Cable: Yes

Data Layer

Data Link: Master/Slave polling
Encoding: APM (Alternating Pulse Modulation)
Error Detection: Parity and CRC
Frame Size: 4 bits input + 4 bits output per slave

Performance

Scan Time: 5ms (62 slaves)
Deterministic: Yes
Real-Time: Yes

Certification

Certification Required: Yes
License Cost: Certification fee for devices
Version: AS-i 5

Advantages & Disadvantages

Advantages

✓Very simple installation
✓Lowest cost per connection
✓Power and data on same cable
✓Flat cable can be pierced for connections
✓No cable shielding required
✓Quick commissioning
✓Flexible topology

Disadvantages

✗Limited to binary sensors/actuators
✗Small data per device (4 bits)
✗Limited distance (100m without repeaters)
✗Not suitable for complex devices
✗Lower bandwidth than alternatives

Common Use Cases & Applications

Binary sensor connections

Simple actuator control

Conveyor systems

Safety sensor integration

Machine tool automation

Packaging machinery

Industry Adoption

Adoption LevelMedium

Market Share5-10% at sensor/actuator level

Geographic PresenceWorldwide, strongest in Europe

Primary Industries

AutomotivePackagingFood & BeverageMaterial Handling

Supported Message Types

Cyclic I/O

Parameter data

Diagnostics

Supported PLC Brands

Siemens

Phoenix Contact

ifm

Pepperl+Fuchs

Balluff

Turck

Protocol Comparisons

AS-Interface vs IO-Link

AS-i for simple multi-drop binary I/O; IO-Link for smart sensors with diagnostics

View Detailed Comparison →

Quick Links

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