Review the following information before calling Technical Support because they will request that you perform many of the procedures or verifications before they will be able to help you diagnose a problem.

If you cannot diagnose the problem, you can contact Comtrol® Technical Support .

If using the DeviceMaster (DeviceMaster PRO, DeviceMaster RTS, and DeviceMaster Serial Hub) NS-Link device driver for Windows, you can check the following:

If using an in-house application, verify that you are addressing the port correctly. In many applications, device names above COM9 require the prefix \\.\ in order to be recognized. For example, to reference COM20, use \\.\COM20 as the file or port name.
Verify that the DeviceMaster has installed by checking the Windows Device Manager to verify that the DeviceMaster is listed properly.

If you need procedures for opening the Device Manager for your Windows system, you can refer to the appropriate substeps under Step 1 of the Checking the Driver Version in Windows page.

Make sure that there is an entry for the DeviceMaster under the Multi-port Serial Adapters section.
Open the Comtrol Drivers Management Console, highligh the DeviceMaster, click the Advanced tab, and review the Device Status window. Ideally, it will state: DeviceMaster is active and Ok.

For Device Status message descriptions, refer to the help system or the DeviceMaster NS-Link User Guide.
After device driver installation, if a port does not open; open the Device Manager, go to Ports COM&LPT and check for notices such as a yellow exclamation mark. If yellow exclamation mark exists, right-click on each and select Update driver. If no yellow exclamation mark exists, check to see if another application might already have the port open.
You can open the Comtrol Drivers Management Console and enable the Verbose Event Log feature on the Device General tab and then reboot the system. Additional information is sent to the Windows Event Log.
If you have not done so, install PortVision DX, which includes Test Terminal for troubleshooting communications on a port-by-port basis and Port Monitor to check for errors, modem control, status signals, raw byte input and output counts.

You can use the Test Terminal procedure below or the Port Monitor (PMon2) and Test Terminal (WCom2) User Guide, which provides procedures for using both Test Terminal and Port Monitor to test ports and communications.
Remove and reinstall the device driver.

Test Terminal Explanation

The following provides background information about the two test procedures discussed for Test Terminal, which is available in PortVision DX.

Send and Receive Test Data: This sends data out the transmit line to the loopback plug, which has the transmit and receive pins connected thus sending the data back through the Rx line to Test Terminal, which then displays the received data in the terminal window for that port. This test is only testing the Tx and Rx signal lines and nothing else. This test works in either RS-232 or RS-422 modes as both modes have transmit and receive capability. A failure in this test will essentially prevent the port from working in any manner.
Loopback Test: This tests all of the modem control signals such as RTS, DTR, CTS, DSR, CD, and RI along with the Tx and Rx signals. When a signal is made HI in one line the corresponding signal line indicates this. The Loopback Test changes the state of the lines and looks for the corresponding state change. If it successfully recognizes all of these changes, the port passes.

A failure on this test is not necessarily critical as it will depend on what is connected and how many signal lines are in use. For example, if you are using RS-232 in 3-wire mode (Transmit, Receive and Ground) a failure will cause no discernible issue since the other signals are not being used. If the port is configured for use as either RS-422 or RS-485 this test will fail and is expected to fail since RS-422 and RS-485 do not have the modem control signals that are present in RS-232 for which this test is designed.

Optionally, you can use the Port Monitor (PMon2) and Test Terminal (WCom2) User Guide, which provides procedures for using both Test Terminal and Port Monitor to test ports and communications.

Using Test Terminal to Test a Port

The following procedure shows how to use Test Terminal to send and receive test data to the serial ports and run a loopback test. This procedures requires a loopback plug. You can build a loopback plug if you are missing the loopback plug shipped with the DeviceMaster using the DeviceMaster Installation and Configuration Guide.

Stop all applications that may be accessing the ports such as RAS, RRAS, or any faxing or production software.

See the appropriate help systems or manuals for instructions on stopping these services or applications. If another application is controlling the port, then Test Terminal will be unable to open the port and an error message will be shown.
From the Start menu, click Programs > Comtrol > Utilities > Test Terminal (WCOM2).
Click File > Open Port and the appropriate port (or ports) from the Open Ports drop list.
Install the loopback plug onto the port (or ports) that you want to test.
Click Port > Send and Receive Test Data.

You should see the alphabet scrolling across the port. If so, then the port installed properly and is operational.
Click Port > Send and Receive Test Data to stop the scrolling data.
Click Port > Loopback Test.

This is a pass fail test and will take a second or two to complete. Repeat for each port that needs testing.

The loopback test tests the modem control (hardware handshaking) signals. It only has meaning in RS-232 mode on serial connector interfaces with full RS-232 signals. If performed under the following conditions, the test will always fail because full modem control signals are not present:
- RS-422
- RS-485
- RJ11 connectors
Close Test Terminal

If both of these tests successfully complete, then the port is operational as expected.

Note
Remember to restart the application once testing of the ports has been completed.

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