¿Qué es el PROTOCOLO HART?
Understanding the HART Protocol
Overview of Automation Systems
- Automation systems utilize various communication protocols to enhance quality and efficiency in industrial process control.
- The HART protocol is one of the most recognized protocols, which will be explored in detail throughout this video.
What is the HART Protocol?
- HART stands for Highway Addressable Remote Transducer, designed for measurement and control applications in industrial processes.
- It is termed a hybrid protocol as it combines both analog and digital communication methods. A single variable can be communicated using an analog signal (4 to 20 mA), while additional information is transmitted digitally.
Communication Mechanism
- The HART communication system operates on standard telephone line principles, utilizing Frequency Shift Keying (FSK).
- Digital signals are superimposed on the 4 to 20 mA analog current signal without affecting its integrity; thus, both types of data can coexist.
Network Configurations
Point-to-Point vs. Multi-Drop
- Devices can operate in either point-to-point or multi-drop configurations:
- Point-to-point: Traditional 4 to 20 mA signals communicate a process variable while additional parameters are sent digitally.
- Multi-drop: Requires only two wires and supports up to 15 field devices with digital transmission of all process values.
Master-Slave Communication Model
- The master-slave model means that communications from slave devices are initiated by a master device, typically a Distributed Control System (DCS), PLC, or PC.
Advanced Communication Modes
Words Mode
- Some HART devices support an optional "words" mode allowing faster data updates (3 to 4 per second).
- In this mode, the master requests continuous messages from slave devices regarding process variables.
Command Structure and Benefits
Command Types
- The HART protocol includes three classes of commands:
- Universal Commands: Recognized by all devices for basic operations like reading variables.
- Common Practice Commands: Functions implemented by many but not all devices.
- Device-Specific Commands: Unique functions tailored for individual field devices.
Advantages of Using HART Protocol