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Products: AS-B
Functionalities: Hardware
Product version: 2022, 2023, 2024

AS-B Servers

arrow1_rotationAS-B Server Models arrow1_rotationAS-B Server Onboard I/O arrow1_rotationOutput Override Function arrow1_rotationBuilt-in Power Supply arrow1_rotationMemory arrow1_rotationSupported Building Standards arrow1_rotationAS-B Server Communication Ports arrow1_rotationAS-B Server Screw Terminals arrow1_rotationAS-B Server LEDs arrow1_rotationReset Functions arrow1_rotationDevice Installation arrow1_rotationWiring arrow1_rotationAS-B Server Software arrow1_rotationServer Replacement Using Restore arrow1_rotationSpecifications arrow1_rotationInternal Configuration

An AS-B server is a powerful automation server that features both onboard I/O and built-in power supply. Like the other automation servers, the AS-B server is a Schneider Electric manufactured embedded device that generally serves as the lowest tier EcoStruxure BMS server within the EcoStruxure BMS. The automation server controls and supervises equipment, typically HVAC equipment. The AS-B server uses its onboard I/O with connected field devices, such as sensors and actuators, to do that.

The AS-B server is installed on DIN rails in cabinets.

action_zoom_plus_stroke  AS-B server

AS-B server

AS-B Server Models

The AS-B server comes in eight models that offer two different sets of I/O point count and I/O mix.


I/O Points

















AS-B servers with “H” in the product name are equipped with a display for output override.

AS-B servers with “P” in the product name are hardware only. An AS-B software package needs to be purchased separately. For more information, see the AS-B Specification Sheet.

AS-B servers with 36 I/O points have the same small footprint as AS-B servers with 24 I/O points.

AS-B Server Onboard I/O

The AS-B server offers a mix of I/O point types that match a wide variety of HVAC applications. Most of the I/O points are universal inputs/outputs, which are highly flexible and can be configured as either inputs or outputs.

For more information, see AS-B Server Onboard I/O .

Output Override Function

The output override function allows you to manually override outputs. This function can be used for testing, commissioning, and maintenance of equipment.

For more information, see Output Override Function .

Built-in Power Supply

The device has a built-in power supply designed to accommodate 24 VAC or 24 VDC input power. The main AC/DC input (L/+ and N/-) is galvanically isolated from the electronics. This removes the risk of damage due to earth currents and permits the input power to be wired without concern for polarity matching.


An AS-B server has two types of memory:

  • 256 MB DDR2 SDRAM (for program execution)

  • 4 GB eMMC memory (for storage)

If a power outage occurs, all important variables are automatically saved to the eMMC memory before complete shutdown. When power returns, this data retention function helps ensure that AS-B can continue to run with the correct set of values.

Supported Building Standards

The AS-B server natively communicates with two of the most popular communication protocols:

  • BACnet: The AS-B server directly communicates to BACnet/IP and BACnet MS/TP networks, which provides access to MP and RP controllers, b3 BACnet devices, and BACnet devices. The AS-B server also supports BACnet/SC applications as a BACnet/SC node or BACnet/SC router, which allows the AS-B server to be in BACnet/SC networks and support applications that connect BACnet/IP or MS/TP networks with BACnet/SC networks.

  • Modbus: The AS-B server natively integrates Modbus RS-485 client and server configurations, as well as IP client and server. This integration provides access to devices that communicate on the Modbus protocol, such as power meters, circuit breakers, and lighting controllers.

AS-B Server Communication Ports

AS-B has the following communication ports:

  • 2 Ethernet 10/100 megabit ports

  • 1 RS-485 port

  • 1 USB host port

  • 1 USB device port

For more information, see AS-B Server Communication Ports .

AS-B Server Screw Terminals

AS-B servers use pluggable terminal blocks, which are easy to install and remove from the device. The terminal blocks are delivered with the device.

For more information, see AS-B Server Screw Terminals .

AS-B Server LEDs

There are five LEDs on the front panel of the AS-B server.

For more information, see AS-B Server LEDs .

Reset Functions

There are four different types of reset for the automation servers: warm start, cold start, reset, and reset to DFU mode. Depending on the type of reset, the automation server can be reset using the reset button or a command from WorkStation.

For more information, see Automation Server Reset Functions .

Device Installation

The AS-B servers are designed for installing on DIN rails in a cabinet.

For more information, see AS-B Server Device Installation .


The wiring recommendations provide guidance regarding wiring of the Central IO modules, automation servers, BACnet/IP devices, RP controller expansion modules, and Operator Display.

For more information, see Wiring .

AS-B Server Software

Before you engineer an AS-B server, install the AS-B server software on the server using Device Administrator. The software is not pre-loaded on the AS-B servers.

For more information, see Installing AS-P or AS-B Software .

Server Replacement Using Restore

Backup and Restore helps assure that automation server data can be restored to a replacement automation server in the event of detected failure, or to the same automation server in the event of data loss. As a precaution, you back up your automation servers regularly so that you can use the most current backup to restore the automation server data to a replacement automation server. You also configure the new automation server to match the name and the network settings of the replaced automation server so the system can identify this automation server when online.

For more information, see Automation Server Replacement Using Restore .


AC input
Nominal voltage
24 VAC
Operating voltage range
+/- 20 %
50/60 Hz
Maximum current
0.5 A rms
Recommended transformer rating
≥15 VA
DC input
Nominal voltage
24 to 30 VDC
Operating voltage range
21 to 33 VDC
Maximum power consumption
10 W
Ambient temperature, operating
0 to 50 °C (32 to 122 °F)
Ambient temperature, storage
-20 to +70 °C (-4 to +158 °F)
Maximum humidity
95 % RH non-condensing
Plastic flame rating
Ingress protection rating
IP 20
198 W x 110 H x 64 D mm (7.8 W x 4.3 H x 2.5 D in.)
Weight, including terminal blocks
0.504 kg (1.111 lb) a
Weight, excluding terminal blocks
0.420 kg (0.926 lb) a
Real-time clock
Accuracy in runtime mode
NTP server
Accuracy in backup mode, at 25 °C (77 °F)
+/-52 seconds per month
Backup time, at 25 °C (77 °F)
10 days
Communication ports
Dual 10/100BASE-TX (RJ45)
1 USB 2.0 device port (mini-B)
1 USB 2.0 host port (type-A), 5 VDC, 2.5 W
2-wire port, bias 5.0 VDC
BACnet/IP and MS/TP, port configurable, default 47808
BACnet/SC, port configurable, no default port
BTL B-BC (BACnet Building Controller) a
Modbus TCP, client and server
Serial, RS-485, client and server
Binary, port fixed, 4444
Non-binary, port configurable, default 80
Encrypted supporting TLS 1.3, 1.2, 1.1 a , and 1.0 a , port configurable default 443
Email sending, port configurable, default 25
Email sending, port configurable, default 587
version 3
Network supervision using poll and trap
Application alarm distribution using trap
333 MHz
SPEAr320S, ARM926 core
256 MB
eMMC memory
4 GB
Memory backup
Yes, battery-free, no maintenance

Internal Configuration

The AS-B servers internal configuration with regards to the signal ground is shown in the following figure.

action_zoom_plus_stroke  AS-B server internal configuration

AS-B server internal configuration

The earth ground terminal (

) of the built-in power supply is connected to signal ground, which is the same as the negative output from the power supply. The purpose of this connection is to comply with EMC directives.

  • Hardware Overview
  • AS-B Server Onboard I/O
  • Output Override Function
  • AS-B Server Screw Terminals
  • AS-B Server Communication Ports
  • AS-B Server LEDs
  • Automation Server Reset Functions
  • AS-B Server Device Installation
  • Wiring
  • Installing AS-P or AS-B Software
  • Automation Server Replacement Using Restore