1 Port RS-232/422/485 Serial over IP Ethernet Device Server

In order for the serial device and your computer to communicate to each other, they both need to be on the same physical network and the same subnet.

To connect your serial device and your computer to the same physical network, plug both devices into the same router. 

Typically, in order for devices to be on the same subnet, the first three numbers of the IP address must match. The fourth number of the IP address must be different, as two devices cannot have the same IP address. For example, if your computer’s IP address is 192.168.0.1, then the subnet is 192.168.0.XXX. You can replace the XXX with any number, as long as it is not currently in use by another device.

To check whether or not an RS-232 serial port is working, perform an RS-232 loopback test by doing the following:

1. If your serial port is not female, convert it by taking a female/female cable or gender changer and plugging it into the serial port.
2. Take a metal paperclip or wire and cross pins 2 and 3. If you look closely at the female end, the pins should be numbered.
3. Open a telnet session on the COM port number of the device that you are testing. To find out the COM port number, refer to the following FAQ: https://www.startech.com/faq/com-port-listing-windows.

Note: To open a telnet session on the COM port, you need a telnet client like PuTTY or Hyper Terminal. Windows XP comes with Hyper Terminal.

4. When the session is open, anything you type into it you should see. The loopback test fails when you cannot see what you are typing.

If the loopback test fails, make sure that the serial cable or gender changer that you are using works and that the adapter is in the correct port. 

You can check multiple ports at the same time by opening multiple sessions, putting the loopback adapter on one port, and trying to type into each session.  When you can see what you are typing, you know that the COM port is working and you can see which port number the physical serial port is. Close the window for the port that you just tested to speed up the testing of the remaining serial ports.

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To troubleshoot this issue, you can try the following:

• Ping the serial device.
• Connect the serial device directly to the computer and ping the device.
• Connect to the web interface (if there is one) or connect using the included software.

Before you begin, make sure that the serial device is on the same network and subnet. For more information, see this FAQ: http://www.startech.com/faq/serial_ip_networks_and_subnets.  If the device starts with an IP address that is not on your subnet, change your IP address to match the subnet being used before you continue.

Ping the serial device

If the serial device and your computer are on the same network and subnet, try pinging the device. 

To ping the device using a computer that is running a version of Windows XP, do the following:

1. Click Start.
2. Click Run.
3. Type ping <IP address> and press Enter. For example, ping 192.168.0.20.

To ping the device using a computer that is running a version of Windows Vista or Windows 7, do the following:

1. Click Start.
2. Click Accessories.
3. Click Command Prompt.
4. Type ping <IP address> and press Enter. For example, ping 192.168.0.20.

To ping the device using a computer that is running a version of Windows 8, do the following:

1. Press the Windows key + X.
2. Click Run.
3. Type cmd and press Enter.
4. Type ping <IP address> and press Enter. For example, ping 192.168.0.20.

To ping the device using a computer that is running a version of Mac OS, do the following:

1. Double-click the hard drive.
2. Double-click Applications > Utilities > Network Utility.
3. Click the Ping tab.
4. Enter the IP address in the Please enter the network address to ping field.
5. Enter the number of packets that you want to test with.

If you receive replies from the IP address, then you can see the device on the network and the issue is with something else.

Connect the serial device directly to the computer

To connect the serial device directly to the computer that you are troubleshooting with, complete the following:

1. Use a crossover Ethernet cable to connect the device and the computer.
2. Try pinging the device again.
3. If you cannot ping the device, use a different computer, Ethernet cable, and serial device (if one is available).

Note: The second computer will need to be on the same network and subnet as the serial over IP device.

4. If you still cannot ping the device, contact support.

Make sure that you are working in a secure environment

1. Unplug the connection between your modem and your router. 
2. Disable any firewalls (especially Windows Firewall), antivirus programs, and security programs that are currently running. 
3. Try accessing the web interface (if the device has one) or try to connect using the included software.

If you still cannot connect to the device's web interface or by using the included software, contact support.

If you can access the web interface or connect using the included software, one at a time turn on your firewalls, antivirus programs, and security programs. Each time that you turn on software and cannot connect to the web interface or by using the included software, add an exception for the serial device to what you last re-enabled.

Virtual COM port

One of the most common applications of a network serial device is to use it to make a standard serial device accessible on a network. To do this, you need to connect a standard serial device to the DB-9 port on the network serial device. Next you need to connect the network serial device to a TCP/IP network using an Ethernet connection, and then install software on a client machine in order to access the network serial device. The software on the client machine communicates with the network serial device and creates (maps) a virtual COM port on your computer system. The virtual COM port is identical to a physical COM port and can be used in the same way.

Serial IP extender

You can use two network serial devices to extend a serial connection over a TCP/IP network. To do this, you need to configure one serial device as a client and the other as a server. The client and server are configured to transmit and receive data to their respective IP addresses and TCP ports. The serial settings must match for all connected serial devices, including the UART on both units. Depending on the serial device that you are using, you can use the provided software or the web interface to set the configurations.

UDP to serial adapter

You can use a network serial device to translate UDP data to a standard serial connection. The serial device is configured to listen for UDP traffic from specific IP addresses and ports, and will asynchronously transmit the data out of the serial port on the device. To do this, you need to configure UART on the network serial device to match the specifications of the serial receiver.