Fault detection:
a. The IP address and port number may not be configured correctly.
b. The serial port parameters may not be configured correctly.
c. RS-485 wiring may be abnormal.

Problem solving:
find the parity bit is error, none parity is modified to mark parity, communication is normal.

Fault detection:
Older version of VSP Manager's RealCom function to receive code algorithm exception, resulting in the serial server to open the WEB function and VSP Manager open RealCom function, the sending and receiving data of the serial port are wrong.

Problem Solving:
After upgrading the VSP management software, the communication is normal.

Check whether the Ethernet port of the serial server is damaged, if it has been damaged, it will cause Ping test packet loss.

Fault detection:
a. MAC address aging.
b. The computer and serial server are not on the same network segment. 
Problem Solving: 
After a period of time to see whether the local connection "!" exclamation mark comes or the computer and serial server can be changed on the same network segment.

Fault detection:
a. The serial server is not powered on.
b. Network cable or fiber optic cable is not connected or poor contact, network cable damage.
c. Network port damage, network cable line error and was not made according to the standard line.
d. Optical port damage, fiber type, fiber wavelength, transmission distance, transmission medium and data format does not match.
e. The serial port server link indicator is damaged. 

Problem Solving:
a. Confirm the communication environment, whether the device is powered on, check the network cable contact problem.
b. Use the Ping command to the IP address of the serial server. If the Ping succeeds, the serial port link LED is broken. If the Ping fails, proceed to the following steps.
c. For electrical port, replace the network cable, computer or serial port to test the electrical port.
d. For optical ports, check whether the fiber type, fiber wavelength, transmission distance, transmission medium, and data format match. If it matches, replace the fiber or optical port for testing.

Check whether the power supply is damaged or whether the positive and negative terminals are connected; whether the power indicator light is on and the power supply is stable.

Problem Detection:
Probably not open session.

Problem Solving:
a. Confirm the communication environment, if you can search the device, link indicator light is also bright, that PC to the serial server can communicate.
b. Check whether the PC and the serial server can Ping successfully. If the Ping fails, change the PC and serial server to the same network segment.
c. Enter the configuration interface of the serial server to check whether the working mode is configured correctly; whether the IP address and port number of the remote virtual serial device and the serial server are consistent.

Fault detection: 
serial port parameters do not match, for no reason to open RealCom function. 

Problem Solving:
a. Confirm the communication environment (whether there is a strong magnetic field around), check whether the communication line is in good contact, and whether the quality of the communication line is OK.
b. Verify that the serial parameters of the test software, serial server, and serial device are matched.
c. When creating a virtual serial port, select "RealCom Mode" for the working mode in the Web configuration interface of the serial server.

a. Equipment supply voltage instability. Troubleshooting: Check the power supply wiring and supply voltage.
b. Network status is unstable. Troubleshooting: Ping the IP address of the serial server to check the network.
c. TCP connection channel is occupied. Troubleshooting: Modify the serial server's IP address and local port number.
d. VSP driver software is modified. Troubleshooting: Install the high version of the VSP driver software.
e. The firewall caused the device to fail to connect. Troubleshooting: Turn off the firewall and anti-virus software.
f. Hardware problems. Troubleshooting: Replace the computer, network cable, serial server.
g. Upper software caused. Troubleshooting: restart the upper software, re-establish the connection.