Common problem

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  • How to use serial device servers?
    There are two commonly used methods:
    a.Use IP address plus port number
    The IP address of the serial device server and the port number corresponding to the non-serial port are used to use the non-serial port. At this time, the serial server works in TCP Server mode. For example, the default IP port 4001 represents COM port 1, 4002 represents COM port 2, and so on.
    b.Use virtual serial port
    After installing the virtual serial port software on the PC side, the corresponding COM port will be found in the device manager of the computer, and then user can use the serial device server.
  • What protocols do serial device servers support?
    A.Seriallink isolated serial device server supports TCP server and UDP protocol.
    B.Seriallink non-isolated serial device server supports TCP Client, TCP server, TCP/UDP Socket, TCP Realport, UDP protocols etc.
  • How to classify serial device servers?
    A.According to the number of serial ports, it can be divided into 1 port, 2 ports, 4 ports, 8 ports, 16 ports, 24 ports, 32 ports, etc.
    B.According to the type of serial port, it can be divided into RS232, RS422, RS485, and RS232/422/485 trinity, or RS232/485 two-in-one.
    C.According to the physical form of serial interface, it can be divided into DB9 interface (standard RS232 type), RJ45 interface (mostly RS232/422/485 type) and terminal interface (mostly 485 type).
    D.According to the type of protection, it can be divided into the type with or without isolation protection.
  • What is the serial device server?
    Serial device server is a device that transfers the data of traditional low-speed RS232/422/485 serial port device to the Ethernet terminal, and realizes virtual COM port by installing virtual serial port driver on the PC terminal or the server terminal.
  • Does the DTU support the Modbus protocol?
    Our DTU does not support the Modbus protocol because different device protocols involve different writing and reading register addresses. Therefore, we only provide transparent transmission of serial data. That is to say, serial data is not processed but sent directly to the server and processed by the server.
  • How to check whether the DTU is connected to the server?
    Our DTU supports concurrency of data on multiple servers. When you set the IP and port number of the server on route A and connect to the server, the LINKA yellow indicator will always be on. The LINKB indicator will always be on when B is connected to the server.
  • How to use DTU? What are the requirements for deploying DTU?
    We will provide each user with a DTU configuration tool. User can set the server-side IP address port number, heartbeat package, registration package and other information, so that the data from the serial port can be converted into IP packets transparently sent to the server.
    Deploying DTU requires you to build a good TCP server and a public network IP.
  • What is DTU? How to classify?
    DTU (Data Transfer Unit) is a wireless terminal device that transparently converts the data of RS232/RS485 serial devices into IP packets and sends them to the server. DTU is widely used in meteorology, hydrology, water conservancy, geology and other industries.
    DTU can be classified into GPRS wireless DTU and 4G LTE wireless DTU according to the network type.
  • What kind of tool software can test Modem?
    Commonly used serial port tools can send AT commands, such as super terminal, serial port debugging assistant, etc.
  • How to use an industrial modem. What function does it have?
    In general, connect your Modem to send AT commands through serial ports to achieve short message and dial-up Internet access.
  • What is 4G LTE Modem?
    Seriallink 4G LTE Modem supports 2G/3G/4G network of China Mobile, Unicom, Telecommunications, which fits all kinds of networks.
  • Which network operators can GSM Modem support?
    China Mobile and China Unicom operate the GSM network in China. Because Unicom's 2G network is currently in the withdrawal state, there are no 2G signals in many areas. If you use GSM Modem, you'd better use China Mobile's card.
  • What's the difference between sending English short messages and Chinese short messages?
    When sending English short messages, user needs to sets the mode to work in TEXT mode with AT command. While sending Chinese short messages requires the use of PDU working module, so Chinese characters need to send the corresponding hexadecimal code.
  • What is AT command?
    AT(attention) command is used to connect and communicate between terminal devices and PC applications. Each AT command line can contain only one AT instruction. For the sending of AT command, the maximum length of 1056 characters (including the last empty character) can be received except AT two characters. 2G 3G 4G Modem has its own AT command manual, but the basic functions of AT commands follow the standard of response, such as SMS (short message), dialing calls (basically the same).
  • How to use the Intetrnet with the Internet of Things(IoT) card?
    The IoT card needs to set up the corresponding APN, user name and password according to the APN form we provide.
  • Does the Seriallink router support APN, VPDN?
    Yes, APN, username, password and VPDN Virtual Private Dial-up can be set up for Internet access.
  • Does the Seriallink router support VPN?
    Yes, it supports L2TP, PPTP, and OpenVPN client.
  • What is the significance of signal indicator light for SLK-R4008 4G router?
    A.Power indicator light: it keeps the light on when powering on.
    B.SYS indicator light: it flickers when the router system starts or restarts. When it finish starting, it will keep the light on, which shows the router system works normally.
    C.3G/4G indicator light: If it keep the light on, it means it has not been registered to 4G network. There are two possibilities: 1. The card is not inserted correctly(the SIM card has not been read). Please insert the card correctly and then re-powering on. 2. Your card has been out of service because of no telephone charges left in your card. In normal condition, this lamp should flash, representing the normal access of the 4G router.
    D.LAN/WAN port indicator light: it will be on when inserting cable. The light will flicker when data exchange happens.
    E.Signal indicator light: The highest signal is 31. Signal 25-31, three lights on. Signal 20-25, two lights on. Signal 15-20, one light on. The signal is in bad condition if it belows 15, and three indicator lights will be off. Under a normal circumstance, two lights should be on.
  • Why does the Seriallink 4G router reboot repeatedly in a few minutes without a card?
    Our router has the function of hardware and software watchdog by default. When logging on to the router, we can configure a PING host IP address in “Service-Watchcat”. If this IP is not accessible, the router will automatically restart every six minutes. While restarting the router, we will give a hard reset signal to the 4G module to restore Internet access by searching the network from a new way. If you connect to a dedicated intranet (not a big one like Baidu), you need to configure a gateway IP or server IP address to Watchcat to prevent the router from restarting continuously.
  • How to Insert SIM Card Correctly in the SLK-R4008 4G Router?
    Firstly, use a sharp object to hold the Yellow button, and then a SIM card tray will be popped up. Secondly, insert a SIM card into the gap angle of the SIM card, ensuring the card core is inserted downward. After the card is plugged in, re-plug the power adapter, and then the router goes into normal working state when starting up.