مبدل TTL به سریال RS485 - تبدیل TTL به RS-485 - ماژول MAX485

DESCRIPTION

The MAX485 TTL to RS-485 Interface Module allows MCUs to use the RS-485 differential signaling for robust long distance serial communications.

PACKAGE INCLUDES:

• MAX485 TTL to RS-485 Interface Module

KEY FEATURES OF MAX485 TTL TO RS-485 INTERFACE MODULE:

• Use MAX485 Interface chip
• Uses differential signaling for noise immunity
• Distances up to 1200 meters
• Speeds up to 2.5Mbit/Sec
• Multi-drop supports up to 32 devices on same bus
• Red power LED
• 5V operation

RS-485 provides for robust serial communications over long distances of up to 1200 meters (4000′) or in electrically noisy environments and is commonly used in industrial environments.  It supports up to 2.5MBit/Sec data rates, but as distance goes up, the maximum data rate that can be supported comes down.

You can think of RS-485 as RS232 on steroids.  The data starts out as typical TTL level serial as far as the microcontroller is concerned while the RS-485 module takes care of converting the electrical signals between TTL and the differential signaling used by RS-485.

Multi-Drop Support for Multiple Devices

A significant benefit of RS-485 is that it supports multiple devices (up to 32) on the same cable, commonly referred to as ‘multi-drop’.

This works by passing the bus through each device where it picks off the signal as it passes through as shown below.

These devices are typically setup in a Master / Slave configuration with one Master and one or more Slave devices.  Since they all share the same bus, to avoid conflict the Slave devices only talk when they are asked for something by the Master such as requesting a temperature reading.