At the core of an EcoStruxure BMS is a SmartX server, such as the SmartX AS-B server. The SmartX AS-B server performs key functionality, such as control logic, trend logging, and alarm supervision, provides built-in I/O, and supports communication and connectivity to the field buses. The distributed intelligence of the EcoStruxure BMS helps ensure fault tolerance against detected faults and provides a fully featured user interface through WorkStation and WebStation.
The SmartX AS-B server is a powerful device with built-in power supply and I/O. The SmartX AS-B server can act as a standalone server using its built-in I/O and also monitor and manage field bus devices. In a small installation, the embedded SmartX AS-B server acts as a standalone server, mounted in a small footprint. In medium and large installations, functionality is distributed over multiple SmartX servers that communicate over TCP/IP.
Capable of coordinating traffic from above and below its location, the SmartX AS-B server can deliver data directly to you or to other servers throughout the site. The SmartX AS-B server can run multiple control programs, manage built-in I/O, alarms, and users, handle scheduling and logging, and communicate using a variety of protocols. Because of this, most parts of the system function autonomously and continue to run as a whole even if communication is interrupted or individual EcoStruxure BMS servers or devices go offline.
The SmartX AS-B server comes in four models with different I/O point count and I/O mix.
Model |
I/O Points |
AS-B-24 |
24 |
AS-B-24H |
24 |
AS-B-36 |
36 |
AS-B-36H |
36 |
SmartX AS-B servers with “H” in the product name are equipped with a display for output override.
SmartX AS-B servers with 36 I/O points have the same small footprint as SmartX AS-B servers with 24 I/O points.
The SmartX 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.
SmartX AS-B servers with 24 I/O points have the following types:
12 Universal inputs/outputs, Ua type
4 Universal inputs/outputs, Ub type
4 Digital inputs
4 Relay outputs
SmartX AS-B servers with 36 I/O points have the following types:
20 Universal inputs/outputs, Ua type
8 Universal inputs/outputs, Ub type
4 Triac outputs
4 Relay outputs
The universal inputs/outputs are ideal for any mix of temperature, pressure, flow, status points, and similar point types in a building control system.
The universal inputs/outputs can be configured to read several different types of inputs:
Digital
Counter
Supervised
Voltage
Current (Ub only)
Temperature
Resistive
2-Wire RTD temperature
2-Wire RTD resistive
As counter inputs, the universal inputs/outputs are commonly used in energy metering applications. As RTD inputs, they are ideal for temperature points in a building control system. As supervised inputs, they are used for security applications where it is critical to know whether or not a wire has been cut or shorted. These events provide a separate indication of alarms and events in the system.
For all analog inputs, maximum and minimum levels can be defined to automatically detect over-range and under-range values.
The universal inputs/outputs are capable of supporting analog outputs of type voltage outputs. Therefore, the universal inputs/outputs support a wide range of devices, such as actuators.
The digital inputs can be used for cost effective sensing of multiple dry contact digital inputs in applications, such as equipment status monitoring or alarm point monitoring. As counter inputs, digital inputs are commonly used in energy metering applications.
The relay outputs support digital Form A point types. The Form A relays are designed for direct load applications.
The triac outputs can be used in many applications to switch 24 VAC on or off for external loads such as actuators, relays, or indicators. Triacs are silent and do not suffer from relay contact wear.
For applications that require more I/O resources, the SmartX IP Controller – IP-IO modules provide a versatile mix of I/O points for any application. For more information, see the SmartX IP Controller – IP-IO Specification Sheet.
SmartX AS-B servers with “H” in the product name are equipped with an LCD display and keys to support manual override control of analog and digital outputs. This function allows you to manually override the outputs for testing, commissioning, and maintenance of equipment.
The override status is readable through EcoStruxure Building Operation WorkStation and WebStation, enabling precise monitoring and more reliable control.
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 AC polarity matching.
A SmartX AS-B server has numerous ports that enable it to communicate with a wide range of protocols, devices, and servers.
A SmartX AS-B server has the following ports:
Two 10/100 Ethernet ports
One RS-485 port
One USB device port
One USB host port
The first Ethernet port is dedicated to the site network. The second Ethernet port is fully configurable. The second port can be configured to extend the site network so that various devices and clients can be connected. Another option is to configure the second port as a separate network, which means that the port can host a private network. If the second port is not used, it can be disabled.
The USB device port allows you to upgrade and interact with the SmartX AS-B server using Device Administrator.
Using a USB Ethernet adapter, you can connect a laptop PC to the USB host port and run Device Administrator, WorkStation, and WebStation to upgrade, configure, and access the SmartX AS-B server.
An EcoStruxure BMS provides a powerful permission system that is easy to manage, flexible, and adapts to all kinds of system sizes. The permission system provides a high standard of authentication. Authentication is done against the built-in user account management system or against Windows Active Directory Domains. The built-in account management system allows an administrator to establish password policies that meet stringent cybersecurity guidelines. When Windows Active Directory is used, the administration costs are lower because users do not have to be managed in multiple directories.
Through any client, the user experience is similar regardless of which EcoStruxure BMS server the user is logged on to. The user can log directly on to a SmartX AS-B server to engineer, commission, supervise, and monitor the SmartX AS-B server and its built-in I/O as well as its attached field bus devices. See the WorkStation and WebStation specification sheets for additional information.
One of the cornerstones of the EcoStruxure BMS is support for open standards. The SmartX AS-B server can natively communicate with two of the most popular standards for buildings: BACnet and Modbus.
A SmartX AS-B server communicates directly to BACnet/IP and BACnet MS/TP networks. The SmartX AS-B servers are BTL-listed as BACnet Building Controllers (B-BC), the most advanced BACnet Device Profile. This capability provides access to an extensive range of BACnet devices from Schneider Electric and other vendors. See the BTL Product Catalog for up-to-date details on BTL listed firmware revisions on BACnet International's home page. A SmartX AS-B server can also serve as a BACnet Broadcast Management Device (BBMD) to facilitate BACnet systems that span multiple IP subnets.
The SmartX AS-B server natively integrates Modbus RS-485 master and slave configurations, as well as Modbus TCP client and server. This allows full access to third-party products and the range of Schneider Electric products that communicate on the Modbus protocol, such as power meters, UPS, circuit breakers, and lighting controllers.
The SmartX AS-B server supports the use of Web Services based on open standards, such as SOAP and REST, to consume data into the EcoStruxure BMS. Use incoming third-party data (temperature forecast, energy cost) over the Web to determine site modes, scheduling, and programming.
EcoStruxure Web Services, Schneider Electric’s Web Services standard, is natively supported in the EcoStruxure BMS servers. EcoStruxure Web Services offers extra features between compliant systems whether within Schneider Electric or other authorized systems. These features include system directory browsing, read/write of current values, alarm receipt and acknowledgement, and historical trend log data. EcoStruxure Web Services requires user name and password to log on to the system.
The Enterprise Server and SmartX servers support MQTT as an option for publishing information to other systems. MQTT is a messaging transport protocol which has become increasingly popular in recent years. With its small footprint, light bandwidth utilization, and simplicity, it is ideal for M2M and IoT communication. Use MQTT to enable the Enterprise Server and SmartX servers to publish values to other systems through any MQTT broker or server, for example, Amazon, Microsoft, or IBM.
EcoStruxure BMS servers can be configured to automatically store all historical data, trend log data, event log and audit trail data, in a high-capacity, open, and well-proven database. If data needs to be available for longer periods of time, an external log storage can be incorporated into the EcoStruxure BMS without the need for extensive engineering work. The database supported is TimescaleDB, which is built on PostgreSQL. The capacity is limited only by the size of the selected storage media.
The data in the external log storage is available natively to the viewers built into the EcoStruxure Building Operation clients and to the built-in reporting functionality. No other software is required to access the data throughout the full retention period. The data is readily available for any analytics software that you already use, due to the open nature of PostgreSQL. Most reporting tools have native support for PostgreSQL.
The TimescaleDB extension to PostgreSQL optimizes the solution for time-stamped data and is well-suited for the EcoStruxure Building Operation historical data.
The system architecture is very flexible. All EcoStruxure BMS servers in an EcoStruxure BMS can write to and read from the same TimescaleDB database, or multiple databases can be used.
You can use the powerful Log Processor functionality for custom processing of trend data for viewing in charts, dashboards and for inclusion in reports. The Log Processor enables advanced calculations on one or multiple trend logs and point values.
Examples of advanced calculations:
Energy usage normalization
Virtual submeters and summaries
Calculation of Mean Kinetic Temperature
Unit conversions
Average, maximum, and mini m um over custom periods
The output of the Log Processor can be saved in the database, including the External Log Storage or calculated automatically on demand.
The EcoStruxure BMS servers provide built-in functionality for basic reporting that can deliver reports in any text format and XLSX, without any dependencies to other external software. Reports for XLSX can be enriched by using advanced functionality such as formulas, conditional formatting, charts and sparklines.
Reports can be generated on schedule, on an alarm event or other custom conditions, and you can get the output delivered via email or written to file.
Unique to the industry, the EcoStruxure BMS servers have both Script and Function Block programming options. This flexibility helps assure that a suitable programming method can be selected for the application.
The SmartX server has a 4 GB eMMC memory, which is used, for example, for the application, historical data, and backup storage. Users can also manually back up or restore the SmartX server to a storage location on a PC or network. Through the Enterprise Server, users have the ability to perform scheduled backups of associated SmartX servers to network storage for even greater levels of protection.
The EcoStruxure BMS servers communicate using the networking standards. This makes installations easy, management simple, and transactions more secure.
Communication between clients and the EcoStruxure BMS servers can be encrypted using Transport Layer Security (TLS 1.2). The servers are delivered with a default self-signed certificate. Commercial Certification Authority (CA) server certificates are supported to lower the risk of malicious information technology attacks. Use of encrypted communication can be enforced for both WorkStation and WebStation access.
IP addressing
TCP communications
DHCP for easy network configuration
DNS for simple lookup of addresses
HTTP/HTTPS for Internet access through firewalls, which enables remote monitoring and control
NTP (Network Time Protocol) for time synchronization throughout the system
SMTP or SMTPS with support for SSL/TLS based authentication, enables sending email messages triggered by schedule or alarm
SNMP enables network supervision and reception of application alarms in designated network management tools
Fasteners easily snap into a locked position for panel installation. The fastener has a quick-release feature for easy DIN-rail removal.
SmartX 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.
The input and output terminals are clearly labeled. EcoStruxure Building Operation WorkStation can generate custom as-built labels for a SmartX AS-B server.
Protection components on the universal inputs/outputs, digital inputs, and triac outputs helps protect against high-voltage short-duration transient events. Universal inputs/outputs configured as current inputs (Ub only) have protection against over current. Universal inputs/outputs configured as voltage outputs have current limits to help protect against permanent short-circuit to ground.
AC input | |
Nominal voltage
|
24 VAC
|
Operating voltage range
|
+/- 20 %
|
Frequency
|
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
|
Environment | |
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
|
Material | |
Plastic flame rating
|
UL94-5VB
|
Enclosure
|
PC/ABS
|
Ingress protection rating
|
IP 20
|
Mechanical | |
Dimensions
|
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
|
a) The weight includes the display and keys, which are 0.022 kg (0.049 lb). | |
Weight, excluding terminal blocks
|
0.420 kg (0.926 lb)
a
|
a) The weight includes the display and keys, which are 0.022 kg (0.049 lb). | |
Agency compliances | |
Emission
|
RCM; BS/EN 61000-6-3; BS/EN 50491-5-2; FCC Part 15, Sub-part B, Class B
|
Immunity
|
BS/EN 61000-6-2; BS/EN 50491-5-3
|
Safety standards
|
BS/EN 60730-1; BS/EN 60730-2-11; BS/EN 50491-3; UL 916 C-UL US Listed
|
Product
|
BS/EN 50491-1
|
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 | |
Ethernet
|
Dual 10/100BASE-TX (RJ45)
|
USB
|
1 USB 2.0 device port (mini-B)
|
1 USB 2.0 host port (type-A), 5 VDC, 2.5 W
|
|
RS-485
|
2-wire port, bias 5.0 VDC
|
Communications | |
BACnet
|
BACnet/IP, port configurable, default 47808
|
BACnet profile
|
BACnet Building Controller (B-BC), AMEV AS-B
|
BACnet certification
|
BTL Certification (BTL Listing
a
, WSPCert)
|
a) See the BTL Product Catalog for up-to-date details on BTL listed firmware revisions on BACnet International's homepage. | |
Modbus
|
Modbus TCP, client and server
|
Serial, RS-485, client and server
|
|
TCP
|
Binary, port fixed, 4444
|
HTTP
|
Non-binary, port configurable, default 80
|
HTTPS
|
Encrypted supporting TLS 1.2, 1.1, and 1.0, port configurable default 443
|
SMTP
|
Email sending, port configurable, default 25
|
SMTPS
|
Email sending, port configurable, default 587
|
SNMP
|
version 3
|
Network supervision using poll and trap
|
|
Application alarm distribution using trap
|
|
CPU | |
Frequency
|
333 MHz
|
Type
|
SPEAr320S, ARM926 core
|
DDR2 SDRAM
|
256 MB
|
eMMC memory
|
4 GB
|
Memory backup
|
Yes, battery-free, no maintenance
|
Display | |
Display resolution
|
128 x 64 pixels
|
Display size
|
36 W x 17 H mm (1.4 W x 0.7 H in.)
|
Display type
|
FSTN monochrome LCD, white color transflective backlight
|
Part numbers | |
SmartX Controller – AS-B-24
|
SXWASB24X10001
|
SmartX Controller – AS-B-24H
|
|
Includes display
|
SXWASB24H10001
|
SmartX Controller – AS-B-36
|
SXWASB36X10001
|
SmartX Controller – AS-B-36H
|
|
Includes display
|
SXWASB36H10001
|
AS-B connector kit (includes terminal blocks)
|
SXWASBCON10001
|
AS-B installer kit
|
SXWASBINS10001
|
Add-on options | |
SW-EWS-1, EcoStruxure Web Services (run-time) option
|
|
Consume only for one SmartX server
|
SXWSWEWSXX0001
|
SW-EWS-2, EcoStruxure Web Services (run-time) option
|
|
Serve & Consume for one SmartX server
|
SXWSWEWSXX0002
|
SW-EWS-3, EcoStruxure Web Services (run-time) option
|
|
Serve & Consume, plus Historical trend log data for one SmartX server
|
SXWSWEWSXX0003
|
SW-GWS-1, Web Services (Generic Consume) option
|
|
For one SmartX server
|
SXWSWGWSXX0001
|
SW-SNMP-1, Alarm notifications via SNMP option
|
|
For one SmartX server
|
SXWSWSNMPX0001
|
SW-SMART-CONNECT, Smart Connector deployment license
|
|
For one Smart Connector deployment
|
SXWSWSCDL100001
|
SW-ASDBTS-1, TimescaleDB connection option
|
|
For one SmartX server
|
SXWSWASDBXS001
|
SW-ASMQTT-1, MQTT publish option
|
|
For one SmartX server (not required if the parent Enterprise Server has a license)
|
SXWSWMQTTXRW01
|
Software requirements | |
External log storage option
|
TimescaleDB 1.2 and later
|
For use of compression: TimescaleDB 2.11 and later
|
|
PostgreSQL version compatible with the TimescaleDB version
|
|
Quality assurance testing has been performed by Schneider Electric with TimescaleDB and PostgreSQL installed natively in Windows 10, Windows Server 2012, 2016, and 2019. Other deployment scenarios have not been tested by Schneider Electric. | |
Universal inputs/outputs, Ua and Ub | |
Channels, SmartX AS-B servers with 24 I/O points
|
12 Ua, Ua1 to Ua12
|
4 Ub, Ub1 to Ub4
|
|
Channels, SmartX AS-B servers with 36 I/O points
|
20 Ua, Ua1 to Ua20,
|
8 Ub, Ub1 to Ub8
|
|
Absolute maximum ratings
|
-0.5 to +24 VDC
|
A/D converter resolution
|
16 bits
|
Digital inputs | |
Range
|
Dry contact switch closure or open collector/open drain, 24 VDC, typical wetting current 2.4 mA
|
Minimum pulse width
|
120 ms
|
Counter inputs | |
Range
|
Dry contact switch closure or open collector/open drain, 24 VDC, typical wetting current 2.4 mA
|
Minimum pulse width
|
20 ms
|
Maximum frequency
|
25 Hz
|
Supervised inputs | |
5 V circuit, 1 or 2 resistors
|
|
Monitored switch combinations
|
Series only, parallel only, and series and parallel
|
Resistor range
|
1 to 10 kohm
|
For a 2-resistor configuration, each resistor must have the same value +/- 5 % | |
Voltage inputs | |
Range
|
0 to 10 VDC
|
Accuracy
|
+/-(7 mV + 0.2 % of reading)
|
Resolution
|
0.5 mV
|
Impedance
|
100 kohm
|
Current inputs | |
Range
|
0 to 20 mA
|
Accuracy
|
+/-(0.01 mA + 0.4 % of reading)
|
Resolution
|
1 μA
|
Impedance
|
47 ohm
|
Resistive inputs | |
10 ohm to 10 kohm accuracy
|
+/-(7 + 4 x 10
-3
x R) ohm
|
R = Resistance in ohm | |
10 kohm to 60 kohm accuracy
|
+/-(4 x 10
-3
x R + 7 x 10
-8
x R
2
) ohm
|
R = Resistance in ohm | |
Temperature inputs (thermistors) | |
Range
|
-50 to +150 °C (-58 to +302 °F)
|
Supported thermistors | |
Honeywell
|
20 kohm
|
Type I (Continuum)
|
10 kohm
|
Type II (I/NET)
|
10 kohm
|
Type III (Satchwell)
|
10 kohm
|
Type IV (FD)
|
10 kohm
|
Type V (FD w/ 11k shunt)
|
Linearized 10 kohm
|
Satchwell D?T
|
Linearized 10 kohm
|
Johnson Controls
|
2.2 kohm
|
Xenta
|
1.8 kohm
|
Balco
|
1 kohm
|
Measurement accuracy | |
20 kohm
|
-50 to -30 °C: +/-1.5 °C (-58 to -22 °F: +/-2.7 °F)
|
-30 to 0 °C: +/-0.5 °C (-22 to +32 °F: +/-0.9 °F)
|
|
0 to 100 °C: +/-0.2 °C (32 to 212 °F: +/-0.4 °F)
|
|
100 to 150 °C: +/-0.5 °C (212 to 302 °F: +/-0.9 °F)
|
|
10 kohm, 2.2 kohm, and 1.8 kohm
|
-50 to -30 °C: +/-0.75 °C (-58 to -22 °F: +/-1.35 °F)
|
-30 to +100 °C: +/-0.2 °C (-22 to +212 °F: +/-0.4 °F)
|
|
100 to 150 °C: +/-0.5 °C (212 to 302 °F: +/-0.9 °F)
|
|
Linearized 10 kohm
|
-50 to -30 °C: +/-2.0 °C (-58 to -22 °F: +/-3.6 °F)
|
-30 to 0 °C: +/-0.75 °C (-22 to +32 °F: +/-1.35 °F)
|
|
0 to 100 °C: +/-0.2 °C (32 to 212 °F: +/-0.4 °F)
|
|
100 to 150 °C: +/-0.5 °C (212 to 302 °F: +/-0.9 °F)
|
|
1 kohm
|
-50 to +150 °C: +/-1.0 °C (-58 to +302° F: +/-1.8 °F)
|
RTD temperature | |
Supported RTDs
|
Pt1000, Ni1000, LG-Ni1000, and JCI-Ni1000
|
Pt1000 | |
Range
|
-50 to +150 °C (-58 to +302 °F)
|
Measurement accuracy
|
-50 to +70 °C: +/-0.5 °C (-58 to +158 °F: +/-0.9 °F)
|
70 to 150 °C: +/-0.7 °C (158 to 302 °F: +/-1.3 °F)
|
|
Ni1000 | |
Range
|
-50 to +150 °C (-58 to +302 °F)
|
Measurement accuracy
|
+/-0.5 °C (+/-0.9 °F)
|
LG-Ni1000 | |
Range
|
-50 to +150 °C (-58 to +302 °F)
|
Measurement accuracy
|
+/-0.5 °C (+/-0.9 °F)
|
JCI-Ni1000 | |
Range
|
-50 to +150 °C (-58 to +302 °F)
|
Measurement accuracy
|
+/- 0.5 °C (+/- 0.9 °F)
|
RTD temperature wiring | |
Maximum wire resistance
|
20 ohm/wire (40 ohm total)
|
Maximum wire capacitance
|
60 nF
|
The wire resistance and capacitance typically corresponds to a 200 m wire. | |
RTD resistive | |
1,000 ohm | |
Range
|
500 to 2,200 ohm
|
Including wiring resistance
|
|
Measurement accuracy
|
+/-(0.2 + 1.5 x 10
-3
x R) ohm
|
R = resistance in ohm | |
Resolution
|
0.1 ohm
|
RTD resistive wiring | |
Maximum wire capacitance
|
60 nF
|
Voltage outputs | |
Range
|
0 to 10 VDC
|
Accuracy
|
+/-60 mV
|
Resolution
|
10 mV
|
Minimum load resistance
|
5 kohm
|
Load range
|
-1 to +2 mA
|
Digital inputs, DI | |
Channels, SmartX AS-B servers with 24 I/O points
|
4, DI1 to DI4
|
Channels, SmartX AS-B servers with 36 I/O points
|
0
|
Absolute maximum ratings
|
-0.5 to +24 VDC
|
Digital inputs | |
Range
|
Dry contact switch closure or open collector/open drain, 24 VDC, typical wetting current 2.4 mA
|
Minimum pulse width
|
120 ms
|
Counter inputs | |
Range
|
Dry contact switch closure or open collector/open drain, 24 VDC, typical wetting current 2.4 mA
|
Minimum pulse width
|
20 ms
|
Maximum frequency
|
25 Hz
|
Relay outputs, DO | |
Channels, SmartX AS-B servers with 24 I/O points
|
4, DO1 to DO4
|
Channels, SmartX AS-B servers with 36 I/O points
|
4, DO1 to DO4
|
Contact rating
|
250 VAC/30 VDC, 2 A, Pilot Duty (C300)
|
Switch type
|
Form A Relay
|
Single Pole Single Throw
|
|
Normally Open
|
|
Isolation contact to system ground
|
3000 VAC
|
Cycle life (Resistive load)
|
At least 100,000 cycles
|
Minimum pulse width
|
100 ms
|
Triac outputs, DO | |
Channels, SmartX AS-B servers with 24 I/O points
|
0
|
Channels, SmartX AS-B servers with 36 I/O points
|
4, DO5 to DO8
|
Output rating
|
Max. 0.8 A
|
Voltage
|
24 VAC +/-20 %
|
Commons
|
COM1 for DO5 and DO6
|
COM2 for DO7 and DO8
|
|
The common terminals COM1 and COM2 can be connected to 24 VAC or to ground. | |
Common voltage, high side output
|
24 VAC
|
Common voltage, low side output
|
0 VAC (ground)
|
Minimum pulse width
|
100 ms
|
For protection from excess current that could be produced by field wiring, follow these instructions:
Connect RET terminal number 4 or 5 to a common chassis/signal ground rail in the control panel using a size 2.5 mm² (13 AWG) or larger wire. The wire must have a current rating greater than or equal to 16 A.
SmartX AS-B servers with 24 I/O points have more RET terminals for connection of I/O returns, so the common chassis/signal ground rail is optional and may not be needed.
Individual 24 VDC power sources to the field must be current limited to maximum 4 A for UL compliant installations, and maximum 6 A in other areas.
For more information on wiring, see Hardware Reference Guide.