Vedard Alarm Security Export Sales Company
Vedard Alarm Security Export Sales Company
News
Precautions for RS485 wiring
Source: https://vedard.com/blog/precautions-for-rs485-wiring/
Date: 2022/05/01
I. RS-485 communication
1. The communication distance of RS485 bus can reach 1200 meters?
RS485 bus transmission only in the ideal environment is possible to make the transmission distance up to 1200 meters. It requires high-quality communication wire, baud rate 2400, only a 485 equipment, which can make communication distance reached 1200 meters, and can communicate does not mean that every communication is normal. Therefore, the actual stable communication distance of 485 bus is far less than 1200 meters. Load much RS485 equipment, wire impedance is not up to standard, wire diameter is too thin, poor quality converter, equipment lightning protection, baud rate and other factors will reduce the communication distance.
2. RS485 bus can carry 128 devices for communication?
In fact, not all 485 converters can take 128 devices. According to the type of 485 converter chip and the type of 485 device chip to judge. Whichever is lower will apply. Generally, the load capacity of 485 chips has three levels: 32, 128 and 256. Theoretical claims are often unattainable in practice. The longer the communication distance, the higher the baud rate, the thinner the wire diameter, the worse the quality of the wire, the worse the quality of the converter, the insufficient power supply of the converter (passive converter), the stronger the lightning protection these will greatly reduce the real load.
3. RS485 bus is one of the most simple and stable and mature industrial bus structure?
This is wrong. 485 bus is an economical traditional industrial bus for device networking. Communication quality needs to be tested and debugged according to construction experience. Although the 485 bus is simple, it must be wired strictly in accordance with the installation and construction specifications.


II. Several requirements for RS485 construction
1. 485+ and 485- data lines must be twisted-pair to each other
2. Use shielded twisted-pair cables. Multiple strands are for reserve; Shielding is for debugging in special cases; Twisted-pair communication because 485 uses the principle of differential mode communication, twisted-pair interference is the best. It is extremely wrong not to use twisted pair cable. security equipment
3. 485 bus must be hand in hand bus structure, resolutely avoid star connection and bifurcation connection. The ac power supply of the device and the chassis must be properly grounded. There are many places where there are triangular sockets on the surface, but there is no grounding at all, so be careful. When the device is properly grounded, the device cannot be struck by lightning. Avoid laying with strong electricity, so as not to interfere with it.

II. Several debugging methods
1. Common ground method: use 1 line or shielding line to connect all 485 equipment GND, so that you can avoid the impact of communication between all equipment potential difference.
2. Terminal resistance method: Connect 120 ohm terminal resistance in parallel on 485+ and 485- of the last 485 device to improve communication quality.
3. Middle section disconnection method: check whether the equipment load is too much, communication distance is too long, the impact of an equipment damage on the whole communication line and other reasons by disconnecting from the middle.
4. Separate wire method: a separate simple and temporary wire to the device, which can be used to rule out whether wiring caused a communication failure.
5. Replace converter method: carry several converters, so you can rule out whether the quality of the converter affects the quality of communication.
6. Notebook debugging method: first ensure that the portable computer notebook is normal communication equipment, replace the customer’s computer, to communicate, if it works well, it indicates that the serial port of the customer’s computer may be damaged or injured.
More News
Wiring and principle of wired detector
WHY CAN SOLAR WIRELESS BEAM INCREASE SECURITY
Why is electrical fire monitoring system needed
Program Beam sensor before installing
Guidance to shop solar wireless security system
Driveway Alarm System
How to test and install solar beam system
Perimeter security should be included in home security system
Perimeter security solution
Install Infrared Beams Detector
Can solar beam be used at gas station or oil depots
Improvement of active infrared detector
Types and features of outdoor security equipment
Security Solution for community safety
Plant area perimeter security solution
Questions of solar beam systems
Automatic fire alarm system and linkage
combustible gas detection is a subsystem
Prevention of fire and carbon monoxide poisoning
Don’t forget home security on Christmas and New Year
Precautions for use of fire alarm facilities after flood
LoRa intelligent wireless fire alarm system
Technical code for fire alarm system in wireless networking
What are the components of the automatic fire alarm system
Replace smoke alarms in time to avoid fire disasters
Gas fire extinguishing controller
Photoelectric beam smoke detector
Wireless fire alarm system
A life-saving smoke alarm in a fire
The three elements of Security Precaution
Alarm System Linkage
Do not use water for these types fire extinguishing
Loss free new anti theft alarm device
Combustible gas toxic gas monitoring system
The different security needs of shops with different size
Security alarm in intelligent parking lot
Linkage of burglar alarm and video surveillance system
Security service management platform
CO carbon monoxide detector
How to set up fire security system
Bus code fire control detector and module
Smoke detector types and application
Smoke detectors types and wiring
How to DIY home security
Fire alarm system types
Lower explosive limit of combustible gas
Home Security Fire Alarm and fire fighting
Connect solenoid valve with gas detector
How to design a 1000 channel large-scale monitoring system
Burglar alarm failure and troubleshooting
How does the access control system link up with fire alarm and surveillance
Debugging of automatic fire alarm system
Home security solution
Why choose TCP/IP RJ45 network alarm control panel?
Integration of security system
Fire alarm system troubleshooting
Security industry development stages
https://vedard.com/blog/conventional-fire-alarm-system-is-suitable-for-small-places/
Setting and Debugging of automatic fire alarm system
https://vedard.com/blog/what-are-the-components-of-the-automatic-fire-alarm-system/
Analysis and solution of false alarm problem
China Top ten brands of burglar alarm system manufacturers
Why is electrical fire monitoring system needed
Training for installing fire alarm system
https://vedard.com/blog
How to build up security service center
How to minimize latency of monitoring systems
Surveillance alarm troubleshooting
What type smoke alarm is better
Difference of sound light alarm and explosion proof alarm
Smart fire alarm system
How to choose active infrared beams
China Security Exhibition 2019 Oct. 28th to 31st
Shopping mall and market interconnection security solution
Intelligent optical fiber perimeter security system
Garden solar alarm lamp
China Chemical plant explosion and Security Consideration
Fire and Explosion in Chemical Plant causes and prevention
Chemical plants fire escape methods and points for attention
Fire Alarm and automatic panel operation training
China Chemical plant explosion and Security Consideration
FIRE DETECTION & ALARM FOR PUBLIC BUILDING AND PREMISES
COMPLETE HOME SECURITY SYSTEM SELF-MONITORED
THEFT & BURGLAR ALARMS FOR HOME SECURITY
What to do with Fire alarm and How to recover alarm devices
How to install PIR and Door Contact for home security
7 causes for false alarm of fire detectors
PIR Passive Infrared Detector installing notice
Automatic fire alarm system terms of manual and automatic control
Is Burglar Alarm System useless?
6 home security solution for different budget and security levels
Electric Fire and Electric Socket
Security Service Network Alarm System upgrade
Explosion proof Fire Alarm Gas Detector Sounder Beacon
Solar Wireless PIR Detectors Features
Fire Alarm System Troubles Resolve Solutions
Fire Alarm Systems Maintenance and trouble shooting
How to avoid CO carbon monoxide poisoning
What is beam system and how does it work
Customers frequently asked questions about Solar Beam systems
How to clean Smoke Detector
Test Method and Notes for the Solar Powered Wireless Beams
Do not use water for these types fire extinguishing
How to disable Smoke Alarm temporarily?
Professional Security System installation standards
Home Security anti-theft knowledge and technology
How to escape from bus fire
How to use fire extinguishers
Flammable gas alarm installation and inspection
Addressable Fire Alarm System illustration
Building Fire Security System
Christmas Home Security Protection cautions
COMPLETE HOME SECURITY SYSTEM SELF-MONITORED
THEFT & BURGLAR ALARMS FOR HOME SECURITY
Wireless Fire Alarm System for commercial security
2017 China Security Fair News
Installing outdoor security cameras
Is Smart Home equal to App controlled Home
2017 China Public Security Exposition & Security Forum
Notice for wiring FC-7448 bus-line alarm system
How to install and debug FC-7448 Commercial Security Alarm System
2017 China Public Security Exposition
Combination of fingerprint lock and home security system
Cold Storage needs fire alarm system
Fire Security for garage, motor repair shop, parking area
FAS design notice
Photoelectric Beam Detection System Solution
How is sensor important for smart home
How to set up driveway alarm systems
Install intruder detector
Upgrade of PSTN network alarm service center
CMS server requirement and operation
meian tech wireless motion detector
Intrusion detector technology and development
intelligent security
Wireless fire alarm system
General Operation of Fire Alarm Control System
Addressable FACP MN300 Instruction
Alarm System Troubleshooting–Part 1 CMS
Alarm System Troubleshooting–Part 2 Alarm Control Panel
Alarm System Troubleshooting–Part 3 Detector
New technology security alarm server EAVS
Fire alarm system design
bus system security alarm technology
Fire Detectors types and selection
Exterior Security Protection
Home Incidents Prevention
Dangerous gas leakage Alarm Device Installation
Hotel Security Solution
Burglar Alarm System Installation Notes
Intelligent Community Security FAQ
Fire Indication on Alarm Control Panel
Fire Defighting System
Fire prevention and escape
Base Station Integrated Security Solution
Community Security Solution
October 25-28, 2016 China Security Exhibition
China Security Alarms Technology
Theft & Burglar Alarms for Home Security
Install Infrared Beams Detector
China Security Alarms Technology
Security System and Smart Home
Home Fire Prevention in Summer
Set up IP camera for home surveillance
Home Security Systems company Karassn cooperation
Pet immune Motion Detectors and the technology
How would you like to manage home security
Program Alarm Systems Solar Beam Detectors
Smoke Alarm types and connection
Question of Focus Security Alarm Systems
Security Alarm Systems Technical Supports
Security Service & DIY home security
Fire Alert Security Alarm Solution Signal Systems
Security Exhibition 2015 in Shenzhen China from 29th Oct.
Advanced Technology Burglar Alarm Systems
Install wireless door magnetic alarm sensor for rolling door
Fire guard read fire alarm manuals and test fire alarm systems before fire happening
Correct wiring Smoke Alarms for Fire Alarm systems
Carbon Monoxide danger
Questions for Solar-powered wireless infrared grating
Smoke Alarm Questions
Alarm system industry trend and alarm system installer job
Conventional Fire Alarm Security Solution
Perimeter Security Solution with Solar Beams
Reliable Wireless Alarm Systems
Smart Home & Secure Home
Flammable gas alarm installation and inspection
Program Alarm System and understand the terms
2014 Security China International Exhibition
Test Method and Notes for the Solar Powered Wireless Beams
Energy saving theft deterrent
Wireless Fire Alarm Solution For Hotel
Additional wireless detectors to existing alarm system
Home Alarm Security Service Development and the importance
Cheap or Quality China Alarms System
DIY alarms or Professional installed alarms
We help buyer buying China Alarm Security Systems
Alarm System Store for DIY without any consultant's advice
Cooperate with Alarm Systems Installers and Security Service
Digital Network Video Server alarm panel
Quick guide to program FC-7448 building security alarm panel
How to choose Motion Sensors from technology views
Advanced technique of intruder detectors
Integration of Security System
Wireless compare with Wired Alarm System