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Trouble shooting the Omni-VI+ serial interface


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Connecting the Omni-VI+ to a computer can sometimes be a frustrating experience due to the many variables in cabling, radio configuration, and logging/control software setup. In order to help you successfully connect your Omni-VI+ to a computer, we have developed a simple diagnostic mode which is built-in on the Omni-VI+ and upgraded Omni-VI’s. In addition, this document includes troubleshooting tips for some common interfacing problems.

To use the built-in Interface Test Mode on the Omni-VI+, you will need a proper interface cable, a computer and “dumb-terminal” program. The interface cable needed for the test is described in chapter 5 of the Omni VI+ manual, but for this test, a simple “three-wire” cable is sufficient and is diagrammed below. The computer program you will need can be a simple DOS based communication program such as “Procomm,” Windows 95 “Hyperterm,” or Windows 3.1 “Terminal” will work. For this test, the communication parameters must be configured to 1200 baud, No parity, 8 data bits, and 1 stop bit. This is often summarized “1200,N,8,1.”

To begin the test on the Omni-VI+ hold down the FM key and turn the Omni on, then release the FM key. If the Omni, cable, computer port and communication program are all working, you will see the following message on the computer screen:

You have Activated the OMNI VI+ Interface Test module
1) Restart Test
2) Echo Test
3) Exit

Each of the three options on the test menu are selected by pressing the appropriate key on the computer keyboard:

Pressing ‘1’ redisplays the introduction screen
Pressing ‘2’ displays the following message, and performs a simple echo back test where each character you type is re-sent by the transceiver.

Characters sent to the radio will be echoed back. If the characters are the same, the radio connection is fine.
To end echo test press (ENTER) or (RETURN).

You should see a double echo of your typed characters. For example, if you type “abc” the echo test will display “aabbcc.”

This test is terminated by pressing the RETURN key on the computer keyboard. Pressing ‘3’ quietly puts the transceiver back into operational mode. At this point, if the Omni-VI+ menu option “Cde” (matrix mode) is turned On, enabling automatic transmission of tuning knob and mode changes, you may see “garbage” on the computer screen. This is normal. What you are seeing is the CIV protocol.

If the transceiver fails the interface test, the most common symptom is simp1y a blank screen on the communication program. There are many possible causes, but there are simple troubleshooting methods to find the problem.

Here are some simple tests you can perform first to help narrow down the problem: 
Try a different device such as a mouse or modem on the com port.
Try a different cable.
Try a different transceiver, if possible.

Here are more unusual causes of problems and possible solutions:

PROBLEM: Cable wired with pins 2 and 3 wrong.
SOLUTION: Examine Manual chapter 5 diagrams and rewire the cable.

PROBLEM: On your computer, the com port you are using for the radio is in conflict with the other com port which shares the same interrupt. For example, COM1 can interfere with COM3 and COM4 can interfere with COM2.
SOLUTION: Try a different com port, or disconnect the device such as a mouse or modem from the other interface.

PROBLEM: The baud rate or other parameters are set incorrectly on the test program. 
SOLUTION: Match interface parameters. The Omni-VI+ Serial Interface Test requires that you use 1200 baud, No parity, 8 data bits and 1 stop bit.

PROBLEM: For logging packages, the radio address is set incorrectly.
SOLUTION: CT and DXBASE, among others, require a computer address other that the default of “04” In addition, some software vendors use hexadecimal notation to describe the address. Be sure to set “C-Id” in menu #2 to the correct value.

PROBLEM: For certain software packages, “matrix mode” must be turned on.
SOLUTION: Menu #2, option “Cde” may need to be “On” in some cases.

PROBLEM: The Omni-VI+ “handshaking” is too slow for some control programs.
SOLUTION: In the Omni-VI+, important transceiver functions such as CW keying and frequency switching take priority over the serial communication operations, and the radio does take some time to respond to certain commands. Fortunately, some programs allow you to set the delay they will allow the transceiver. Look for a parameter in your software for, “timeout” or “retries”.

Note: for many logging/control programs, failure of the transceiver appears as a “time out” error, even though the cause could be anything that prevents communication; not just a timing problem.

In general, to successfully control the Omni-VI+ from a logging/control program, you must have the right cable, correct configuration of serial port parameters for both transceiver and the computer, and have the CIV parameters for Matrix mode and Address set correctly.

Three-wire Cable:

25-pin to 25-pin:
Computer Transceiver
(female) (male)
2 2
3 3
7 7
9-pin to 25-pin
Computer Transceiver
(female) (male)
2 3
3 2
5 7

Please note that pins 2 and 3 are reversed on the 9-pin connector.

If you use these tests and determine that the Omni-VI+ is the problem, please contact the Ten-Tec service department at (865) 428-0364 and we will be happy to assist you.