User Manual for USR-N668 8-Channel Serial Port Server -8-Channel RS232/RS485/RS422 to Ethernet - Modbus Product Center

I. Product Introduction

USR-N668is an industrial grade device that implements transparent data transmission between RJ45 network ports and RS232/RS485/RS422 interfaces. It is an 8-channel serial port server8-way serial port serverlaunched by Jinan Youren Internet Technology Co., Ltd. This device is equipped with an ARM processor, which has the characteristics of low power consumption, fast speed, and high stability.Low power consumption, fast speed, and high stabilityThe characteristics.TCPUsers can easily complete the networking transformation of embedded devices using it, saving development time and labor costs. This series of products has been successfully applied in complex network environments such as banks, highway surveillance, large enterprise networks, video surveillance systems, and fiber to Ethernet conversion.

2, Core functional features

Function	Detailed Explanation
2-channel Ethernet ports	10/100Mbps adaptive, supports AUTO-MDIX cross direct connection automatic switching
8-channel serial ports	Each serial port supports RS232/RS485/RS422 three modes that can be switched
IP acquisition method	DHCP/static IP two methods
working mode	TCP Server, TCP Client, UDP Client, UDP Server, Httpd Client, SSL Client, a total of 6 types
dual socket function	Each channel supports dual sockets, and can send data to two different servers when acting as a client
TCP Server connection number	Maximum support Connect 16 clients simultaneously
Heartbeat Package&Registration Package	Customize heartbeat and registration packages to ensure reliable connections and prevent dead connections
Modbus TCP to RTU	Support automatic conversion from Modbus TCP protocol to Modbus RTU protocol
Timeout restart/reconnect	No data timeout restart and timeout reconnection, time can be customized
MAC address modification	MAC address can be modified, factory burned with globally unique MAC address
DNS Domain Name Resolution	Support DNS domain name resolution, with customizable DNS server addresses
remote management	Support remote monitoring and remote firmware upgrade
DDNS dynamic domain name	Support DDNS dynamic domain name resolution function such as peanut shells
time synchronization	Support network time synchronization+built-in RTC real-time clock
Planned tasks	Users can customize timed execution of device related instructions
configuration method	There are three ways to configure web pages, software settings, and AT commands
Virtual Serial Port	Supporting USR-VCOM virtual serial port software
VPN-PPTP	Support PPTP protocol VPN link
GRE Tunnel	Supports GRE Tunnel Protocol
Factory Reset	Supports both software and hardware factory reset

III. Technical Parameters

3.1 Electrical Parameters

Classification	Parameter Names	Values
Hardware Parameters	Operating Voltage	AC 85~265V, 50/60Hz
	Power consumption	1.6W
	Network port specifications	RJ45, 10/100Mbps, cross direct adaptive
	Number of network ports	2 channels
Serial port parameters	Serial port specifications	RJ45
	Number of serial ports	8 channels x RS232/RS485/RS422
	Baud rate range	300~115200 bps
	default parameter	None/8/1
software parameters	network protocol	IP, TCP/UDP, ARP, ICMP, IPv4, HTTP, SSL
	IP acquisition method	Static IP/DHCP
	domain name resolution	Support, customizable DNS server address
	Passthrough method	TCP Server/TCP Client/UDP Server/UDP Client/Httpd Client/SSL Client
	web cache	10KB, Serial port cache 10KB

3.2 Other parameters

Parameters	Values
Shell protection level	IP30
Dimensions	482 × 185 × 45 mm (rack mounted)
Operating temperature	-40 ℃~+85 ℃
Storage temperature	-40 ℃~+105 ℃
Operating Humidity	5%~95% RH (no condensation)
Static electricity level (EN61000-4-2)	Level 4
Pulse group level (EN61000-4-4)	Level 4
Surge level (EN61000-4-5)	Level 3
Average transmission delay	≥50ms
Packaging mechanism	50ms packaging time, 1472 byte packaging length

IV. Hardware Introduction

4.1 DIP Switch (Serial Mode Switching)

There is a DIP switch setting window on the back of the device, which can only be seen by removing the screw with a Phillips screwdriver. There are a total of 16 dialing codes (8 serial ports x 2/channel). Once set, it will be permanently used.

Serial Port Mode Corresponding Dialing Settings

Communication Method	Dialing 1 (from left to right)	Dialing 2 (from left to right)
RS232	0 (bottom)	0 (bottom)
RS485	1 (top)	1 (top)
RS422	1 (top)	0 (bottom)

Note: silk screen printing is the standard, dial up to represent 1, dial down to represent 0; Factory default is RS485 mode (11)

4.2 Serial port pin definition (RJ45 interface)

Serial number	Name	Function description
1	232_TX/422_Z/485-B1	232 send; 422 signal Z; 485 signal B
2	232_SX/422_SA1	232 reception; 422 signal A
3	422_Y/485A_1	422 signal Y; 485 signal A
4	422-B1	422 signal B
5	NC	empty pin
6	GND	232 signal ground
7	NC	empty pin
8	NC	empty pin

Note: RS232/RS485/RS422 can only work in one way at a time; Correct dial switch coordination is required; Using 8-core Ethernet cable and crystal head to make communication cable

4.3 Indicator light description

Indicator light name	Identification	Color	Status Description
Power Indicator	PWR	Red	Always On After Power On
Work Indicator	WORK	Green	Cycle Flashing After Startup (500ms On/500ms Off)
Status Indicator	STATE	Red	Function Undefined (Reserved)
Ready indicator	READY	Green	The device is working normally and always on; Unworking Long Off
Serial Port Send x 8	TXN	Red	Serial Port N Send Indicator, Blinking When Data is Available
Serial Port Receive x 8	RXN	Green	Serial Port N Receive Indicator, Blinking When Data is Available

V. Default Parameters

Project	Default Values
Username	admin
Password	admin
IP Address	192.168.0.7
Subnet Mask	255.255.255.0
Default Gateway	192.168.0.1
Working Mode	TCP Server
Target Port	20001~20008 (1st~8th Road)
Local Port	20001~20008 (1st~8th Road)
Target IP	192.168.0.201
Serial Port Baud Rate	115200
Serial port parameters	None/8/1

VI. Detailed explanation of working modes

6.1 TCP client working mode

• Actively initiate connection: As a client, actively initiate a connection request to the server and establish a connection
• KeepAlive keep alive: Send a probe packet after waiting for 60 seconds for the first time to detect abnormal disconnection (formula: 60+5 * 3=75 second detection cycle)
• Applicable scenarios: Data interaction between devices and servers, the most commonly used networking communication method
• Local port recommendation: Set to 0, use a random port number to avoid being blocked
• Cross public network requirements: The server must have a public IP or domain name

6.2 TCP Server working mode

• Passive listening: Actively listening to the set local port and responding to connection requests
• Maximum number of connections: Can accept up to 16 simultaneous connections from clients (local port cannot be set to 0)
• Broadcasting mechanism: The serial port receives data and sends it to all connected clients at the same time
• Applicable scenarios: Multiple computers/phones accessing devices simultaneously in the local area network
• Cross public networkPort mapping needs to be done on the router

6.3 UDP Client Working Mode

• Connectionless transmissionNo need to establish a connection, just specify the IP and port to send data
• Directional communicationOnly communicate with the target port of the target IP
• Broadcast supportTarget: 255.255.255.255 to achieve full network segment broadcasting (firmware 4015+supports xxx.xxx.xxx.255 network segment broadcasting)
• Not supporting multicast

6.4 UDP Server Working Mode

• Do not verify the source IPAfter receiving UDP data, change the destination to the source IP/port
• Recent communicationSend data to the nearest communication IP and port
• Applicable scenariosScenario where multiple network devices communicate at high speed and do not want to use TCP

6.5 Httpd Client Working Mode

• Serial port to HTTP conversionSend request data to a specified HTTP server via serial port
• Automatically add header informationURL and header information are automatically added by 668
• Return data processingYou can choose whether to remove the header and send it to the serial port

6.6 SSL Client Working Mode

• Encrypted transmissionSupport SSL encryption on TCP connections
• Optional encryption methodNo need to manually select encryption parameters

7, Detailed Explanation of Featured Features

7.1 SocketB dual channel function

In addition to the main Socket transparent transmission, there is also a Socket B function. The data received by the serial port is sent to both SocketA and SocketB simultaneously, and vice versa. Can be used for data backup links, with the same working mechanism as SocketA.

7.2 Heartbeat Packet Function

Parameters	Description
Heartbeat Direction	Can be sent to the network or serial port (not running simultaneously)
Custom Content	Maximum 40 bytes
Default Interval	30 seconds (range 1-65535 seconds)
Effective Mode	TCP Client and UDP Client Modes

7.3 Registration Packet Function

Type	Description
Connection Registration Packet	Sent immediately after connection establishment, used to identify device source or authorize verification
Data Carrying Registration Packet	Access registration packets at the forefront of data for protocol transmission
Full registration	Both of the above are executed
MAC registration package	Send a 6-byte MAC address when establishing a connection

Custom registration package can be up to 40 bytes long and supports hexadecimal input

7.4 Modbus TCP to Modbus RTU

Suitable for data conversion scenarios where the serial port side uses Modbus RTU protocol and the network side uses Modbus TCP protocol. Default closed, can be opened through a webpage. Good performance in high-frequency data collection.

7.5 VPN-PTP and GRE Tunnel

• PPTPSupport MPPE/MPPE-128 encryption; PAP/CHAP/MSCHAP/MSHAPv2 authentication; The default LCP interval is 300 seconds; MTU defaults to 1500
• GRE: Set four parameters: remote address, local address, remote tunnel address, and local tunnel address

8. AT instruction configuration

8.1 Enter AT Command Mode

1. Input on UART“+++The module returns a confirmation codea"
2. Enter the confirmation code on UART“aThe module returns+OKEnter command mode

Note: Input "+++" and "a" does not echo; T1 needs to be greater than the serial port packaging interval; T2/T3 less than 300ms; T5 less than 3 seconds

8.2 Common AT Instructions

Instruction	Functional Description
AT+WANN	Set and query IP acquisition method, IP/subnet mask/gateway parameters
AT+DNS	Set and query DNS server addresses
AT+SOCK	Set Socket working mode/target IP/target port
AT+RELD	Restore factory settings
AT+ENTM	Exit command mode and return to transparent transmission mode

8.3 Error Code List

error code	Explanation
-1	Invalid command format
-2	Invalid command
-3	Invalid operator
-4	Invalid parameters
-5	Operation not permitted

9, Method for restoring factory settings

1. Hardware buttonsPress the Reload button for 5 to 15 seconds to restore the factory (not executed for less than 5 seconds or more than 15 seconds)
2. set up softwareBy configuring the software's factory reset function
3. AT commandsEnter AT command mode, inputAT+RELD
4. Web loginClick on the factory reset button on the webpage

10, Quick Start Guide

10.1 Hardware Preparation Checklist

1. USR-N668 equipment x 1
2. AC220V power cord x 1
3. Mother to mother serial port cable x 1
4. DB9-M to RJ45 × 1
5. Network cable x 2
6. One computer (with built-in RS232 port or USB to 232 converter)

10.2 Connection steps

1. Connect the N668 serial port to the computer through a serial cable
2. Connect the 668 Ethernet port to the PC Ethernet port using a network cable
3. After confirming the hardware connection is correct, connect the power adapter for power supply
4. Confirm the current serial port mode (factory default RS485) through the back dial window

10.3 Network environment check

1. Turn off the computer firewall and antivirus software
2. Turn off unrelated network cards and only keep one local connection
3. If directly connected to a PC, set the static IP and 668 in the same network segment (such as 192.168.0.201)

10.4 Default testing process

1. Open the "USR-TCP232 Test. exe" debugging assistant
2. Select TCP Client mode in the network area, target IP: 192.168.0.7, port: 20001
3. Set the serial port to 115200, None/8/1, open the serial port
4. Conduct transparent transmission test for bidirectional data transmission and reception between serial port and network

11, Data Download

Product Model:USR-N668 V1.0.5Instruction manual document:USR-N668_V1.0.5.pdfOfficial website:www.usr.cn(Jinan Youren Internet of Things Technology Co., Ltd.)http://h.usr.cnTechnical Hotline: 4000-255-652/0531-88826739sales@usr.cn

12, Application scenarios

• Bank system network terminal access
• Networking of ETC/Toll System Serial Devices on Highways
• PLC/Instrument/Sensor Networking in Large Enterprise Networks
• Networking of serial control devices for video surveillance systems
• Complex network environment of fiber to Ethernet conversion
• Remote monitoring of serial port equipment in factory automation production line
• Intelligent building/access control/attendance system networking
• Medical equipment serial port data collection and upload