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 |