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Cannot Open COM Port on the Ether-Serial Link
11-14-2011, 07:57 PM, (This post was last modified: 11-21-2011, 04:27 PM by admin.)
Post: #1
Cannot Open COM Port on the Ether-Serial Link
The ESL is a virtual Com Port that is always present in the device manager regardless of whether or not the device can be accessed.

There are two common reasons why you might have trouble connecting to the Com Port of an ESL.
  • The ESL is unreachable
  • The Com Port is in Use by another user

The first thing to do is to verify that you are able to communicate to the device over the network; this is best done by pinging the IP Address of the ESL.
  1. Determine the IP Address of the ESL. This can be found in the Lava Manager by right clicking on the device and going to properties.
  2. Once you know the IP Address of the device open up a command Window.
  3. From the Start Menu select Run and type “cmd” into the command box, this will open up a command Window.
  4. Type the following command “ping <ipaddress>”. For this example I’m assuming the IP Address of the ESL to be (i.e. ping
  5. If you’re able to contact the ESL through the network you will see a “Reply” come back from the IP Address, if not you will be informed that the “Request timed out”.
  6. If the ESL isn’t responding to a ping that is a good indication that there is a network configuration problem, the most common problem is that the IP Address of the ESL is in a different subnet than the PC (i.e. if the IP Address of the PC is then the ESL needs to be in a similar range 192.168.1.XX).
    • Note: Even though you can see the ESL in the Lava Manager that doesn’t mean that you’ll be able to communicate with it through the network.
Once you have verified that you can connect to the ESL through the network, the next best thing to it would be to open the embedded webpage of the ESL.
  1. Open your web browser, type in the IP Address of the ESL and press Enter.
  2. If the ESL is available it should serve up a webpage displaying its MAC Address, IP Address, firmware revision, port available etc.
  3. If the webpage fails to be displayed there is a good chance that the IP Address you received a reply on was not actually the ESL, this can happen when two devices are sharing an IP Address. It would be wise to unplug the ESL and ping the IP Address again. With the ESL off you shouldn’t receive a response, if you’re getting a reply with the ESL powered down then it would be advisable to change the ESL to a different IP Address.
If the web page is being displayed this is a good indication that you are communicating with the ESL through the network. At this point it is possible that the reason you can’t connect to the ESL is that the port is currently in use by another system.

To check the current status of the port look on the Web Page that you just pulled up, in the Activity Column any port that is in use will be displayed as Active, and any port that is currently active cannot be connected to until it is Inactive.

At this point if you’re able to view the webpage of the ESL and the port you are trying to connect to is currently Inactive then the issue might have to do with either the software that you’re using or a configuration issue within the ESL. At this point it would make sense to open a connection to the Com port through Hyperterminal and if that fails restore the Factory default settings on the ESL.

Applies to:
- ESL Units

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