Creating a Loopback for Testing

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A loopback connection is one where the signal being sent also comes back to the sender -- similar to an echo. This allows you to test a line (including the devices on it) to verify its correct operation.

 

Creating a loopback with a Device Server is rather simple. You just have to make sure you're working on RS232 (if your Device Server is also capable of other serial protocols) and connect serial pin #3 (TX, output) to serial pin #2 (RX, input), like so:

 

an008_loopback

 

For this setup to work:

 

Connect the DS to the network, and using DS Manager, set RTS/CTS Flow Control to Disabled or remote.

 

Follow the steps laid out on Establishing a TCP/IP Connection with a Device Server and create a connection with your DS from HyperTerminal.

 

Now, anything you will send will get back to you. Just type, and see what you type on the screen. To confirm that this is indeed a loopback, just disconnect pin #2 from pin #3 on the DS, and you'll no longer see what you type.