RS485-HUB-2P User Guide

Overview

Introduction

RS485-HUB-2P is an industrial-grade isolated RS485 hub that can expand one RS485 host port into two RS485 slave ports. It can achieve RS485 network relay, expansion, and isolation functions. It adopts a terminal type power supply access and rail-mounted housing design, making it easy to install and cost-effective. It is suitable for fields such as data acquisition, IoT gateways, security IoT, and intelligent instrument monitoring.

Specifications

Interface standards	Compliant with RS485 standard
Physical interface	RS485 screw terminals
Communication rate	300～460800bps baud rate (adaptive)
Supported nodes	Each RS485 port supports up to 32 nodes
Communication distance	1200m (9600bps), the higher the communication rate, the shorter the distance
Operating mode	RS485 two-wire (A, B), half-duplex transparent transmission
Power Supply	DC 5~36V
Operating temperature	-45 ~ +85℃
Environment humidity	<95%RH
Transmission medium	Normal parallel cables/twisted-pair cables

Interfaces

Interfaces	Description
+5～36V, GND	Power supply terminal input
OUT1A～OUT2A, OUT1B～OUT2B	RS485 slave ports 1~2
485A, 485B	RS485 host port
P1～P2	RS485 1～8 slave port data reception indicators
RXD	485 host port data reception indicator
TXD	485 host port data transmission indicator
POWER	Power indicator

Function Description

Extension

When the host RS485 device needs to connect 2 RS485 slave stations via a star connection, connect the host station to the host port of the RS485-HUB-2P, and connect the slaves to the slave ports of the RS485-HUB-2P. This can prevent interference between RS485 and achieve effective isolation.

Isolation

Connect one end of the RS485 to the RS485 host port, and the other end to any RS485 slave port. At this point, the RS485 line is effectively isolated, providing protection against lightning strikes and interference. This effectively protects the other end of the RS485 device from being damaged by high voltage and strong current.

Relay

When RS485 cables exceed 1200 meters or longer distances, signals will attenuate and interference will increase. By using RS485-HUB-2P, the communication distance can be extended.

Hardware Connection Diagram

RS485 Point-to-Point Relay Communication

RS485 1-to-2, point-to-point, half-duplex, relay communication

RS485 Point-to-Multipoint Relay Communication

It supports star-type segmentation connection for RS485 bus, enables flexible networking, and features signal relay and amplification functions

RS485 Point-to-Multipoint Relay Communication

It supports the cascading of multiple RS485 devices, solving connectivity issues in large systems with multiple node networking, ensuring stable and reliable signal amplification

Dimensions

FAQ

Question: How to connect multiple RS485-HUB-2P to the same RS485 interface of the same device?

Answer:

It is a device with one host and eight slaves, purely hardware wired, and must meet three prerequisites:

1. The serial port parameters are consistent;
2. The communication protocol is half-duplex, one question and one answer type, such as the Modbus RTU protocol;
3. The device addresses are different. Seven 485 slave ports can be connected to one 485 device or a 485 bus
4. The scanning cycle time set by the program should not be too short. Adjust the time as long as possible, as the device needs sufficient time
5. Cannot be connected in parallel to the host's 485 port; it must be connected in handshake cascading, as shown in the figure below:

Question: We have purchased RS485-HUB-2P, can you send us its protocol?

Answer:

This device is mainly an extension of the physical layer, which does not involve specific communication protocols, but ensures that the electrical characteristics of the RS485 standard, such as differential signal transmission, multi-point communication, etc., are supported at the hardware level.
The device does not contain any functionality to change its role or control communication protocols; it is merely a transparent signal forwarder.

Question: What is the power of RS485 HUB-2P?

Answer:

Question: We have purchased RS485-HUB-2P, can you send us its protocol?

Answer:

This device is mainly an extension of the physical layer, which does not involve specific communication protocols, but ensures that the electrical characteristics of the RS485 standard, such as differential signal transmission, multi-point communication, etc., are supported at the hardware level.
The device does not contain any functionality to change its role or control communication protocols; it is merely a transparent signal forwarder.