In this note, we are going to know about the HART Communication Networks, like Point to Point, Multidrop, Wireless etc. Welcome to Poly Notes Hub, a leading destination for engineering notes.

Author Name: Arun Paul.

HART Communication Networks

HART (Highway Addressable Remote Transducer) is a hybrid analog-digital communication technology for industrial automation. It enables communication between a host system (e.g., a PLC, DCS, or PC) and smart field devices over existing 4-20 mA wire.

There are three types of HART Communication Network

• Point-to-Point Network
• Multidrop Network
• WirelessHART Network

1. Point to Point Network

A Point-to-Point HART network is a communication configuration in which a single host device (such as a PLC, DCS, or HART communicator) connects to a single field device via a 4-20 mA analog loop. The HART protocol allows a digital signal to be superimposed over an analog current signal.

Key Point of Point-to-Point Network:

• Analog + Digital communication
• Most commonly used configuration

2. Multidrop Network

A Multidrop HART network enables a single host to interact with up to 15 field devices using the same pair of wires. In this design, all devices use a fixed loop current (usually 4 mA) and communicate purely digitally.

Key Point of Multidrop Network:

• Digital-only communication
• Each device has a unique address (1–15)

3. Wireless HART Network

WirelessHART is a HART protocol modification that allows smart field devices to communicate wirelessly with a host system over a mesh network. Devices communicate wirelessly with one another and a central gateway that connects them to the control system.

Key Point of Wireless HART Network:

• No wiring required
• Based on IEEE 802.15.4 standard
• Ideal for remote, mobile, or hazardous environments

Difference Between HART Networks

Features	Point to Point	Multidrop	Wireless
Signal Type	Analog + Digital	Digital Only	Wireless Digital
Analog Loop Current	4-20 mA	Fixed (4 mA)	None
No. of Devices	1	Up to 15	100+ possible
Wiring Cost	High	Medium	Low
Speed	Fast	Slower	Variable
Best Use	Control loops	Monitoring systems	Remote/Hazardous sites