7

￿ ￿        

Control Keypad

77(96)

7.4.8Modbus interface

NXL has a built-in Modbus RTU bus interface. The signal level of the interface is in accordance with the RS-485 standard.

RS-485 Transceiver

Control terminal

 

 

 

 

 

 

 

 

 

 

RS-485 A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RS-485 B

 

 

 

 

 

 

 

 

 

 

Terminal resistor 120Ω

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

X7 -> MF2-MF3

 

 

 

 

 

 

 

 

 

 

X9 -> MF4-MF6

 

 

 

 

 

 

 

 

 

 

Protocol:

Modbus RTU

Baud rates:

300, 600, 1200, 2400, 4800,

 

 

 

 

 

 

 

 

9600, 19200, 38700, 57600 (bit/s)

Signal level:

RS-485 (TIA/EIA-485-A)

Input impedance:

2 kΩ

7.4.8.1Modbus RTU protocol

Modbus RTU protocol is a simple but effective fieldbus protocol. Modbus network has a bus topology, where every device has an individual address. With the help of the individual bus addresses the commands are directed to the single devices within the network. Modbus supports also broadcast -type messages, which are received by every device of the bus. Broadcast messages are sent to the address ’0’ which is reserved for these messages.

The protocol includes CRC error detection and parity check for preventing the handling of messages containing errors. In Modbus the data is transferred in hex mode asynchronically and a break of approximately 3.5 characters is used as an end character. The length of the break depends on the used baud rate.

Function code

03

04

06

16

 

Function name

 

Address

 

Broadcast

 

 

 

 

 

 

 

 

 

 

messages

 

 

Read Holding Register

 

All ID numbers

 

No

 

 

Read Input Register

 

All ID numbers

 

No

 

 

Preset Single Register

 

All ID numbers

 

Yes

 

 

Preset Multiple Register

 

All ID numbers

 

Yes

 

Table 7-12. Modbus commands supported by NXL

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Image 77
Honeywell NXL user manual Control Keypad 7796, Modbus interface, Modbus RTU protocol

NXL specifications

Honeywell NXL is an advanced building management system designed to optimize the efficiency of HVAC, lighting, and security systems within commercial buildings. It incorporates cutting-edge technologies to enhance operational performance, improve energy savings, and provide a comfortable environment for occupants.

One of the standout features of Honeywell NXL is its integration capabilities. The system allows seamless connections between various subsystems, facilitating a unified approach to building management. This interoperability means that data from different systems can be aggregated, analyzed, and applied to enhance overall building performance.

The Honeywell NXL employs a user-friendly interface that empowers facility managers to easily navigate through critical information. The intuitive dashboard offers real-time analytics and visualizations, providing insights into energy consumption, system performance, and occupant comfort. Users can quickly identify inefficiencies and make informed decisions to improve operational effectiveness.

In terms of technologies, Honeywell NXL utilizes IoT connectivity, which enables devices and systems within the building to communicate with one another. This connectivity allows for remote monitoring and control, which is essential for effective facility management. By leveraging IoT technology, facility managers can receive alerts, conduct diagnostics, and perform maintenance proactively, reducing equipment downtime and avoiding costly repairs.

Another significant characteristic of the Honeywell NXL is its robust data analysis capabilities. The system collects vast amounts of data from sensors and connected devices, which is then processed to identify patterns and trends. This analytical approach not only aids in energy management but also enhances occupant comfort by adjusting parameters in real-time based on occupancy and environmental conditions.

Energy management is a critical issue for modern buildings, and Honeywell NXL addresses this with advanced optimization strategies. The system can implement demand response capabilities, adjusting energy usage based on peak periods or grid demands, ultimately saving costs and reducing environmental impact.

Moreover, Honeywell NXL places a strong emphasis on security features. Its design includes integrated surveillance and access control systems, ensuring the safety of occupants while facilitating efficient access management.

In summary, Honeywell NXL is a comprehensive building management solution that combines user-friendly design, IoT connectivity, advanced data analytics, energy optimization, and enhanced security features. Its ability to integrate various building systems makes it an essential tool for contemporary facility management, promoting efficiency and sustainability in building operations.