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KIO2 connection with computer

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Pierre Vallee

KIO2 connection with computer

I installed the KIO2 about one year ago. It worked fine. I now have a problem with it. I can't get a connection between the K2 and the computer using the K2 Remote V1.0 Beta program. The computer com1 setting is fine and the K2 port is ON. In testing the cable between the K2 and the computer with a line tester, I get a "no reading" on pin 2 .

In doing the voltage checks for U1, I find readings of 12.77v on pin 5 (should be -8) and 0v on pin 12 (should be 5). I believe the circuit diagram shows these pins being part of the transmit circuitry (pin 2). Could U1 be my problem? Any suggestions. Thanks

Pierre
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Mike S-8

Re: KIO2 connection with computer

At 05:26 PM 11/7/2004, Pierre Vallee wrote...
>In doing the voltage checks for U1, I find readings of 12.77v on pin 5 (should be -8) and 0v on pin 12 (should be 5). I believe the circuit diagram shows these pins being part of the transmit circuitry (pin 2). Could U1 be my problem? Any suggestions. Thanks

U1 is an EIA-232 transceiver. It converts TTL level to EIA ("RS-232") levels. The voltages you describe show it is operating correctly - when pin 12 is at 0, pin 5 should be more than +3 positive ("space" level). When pin 12 is at 5, pin 5 should be more than -3 negative ("mark" level. You'll notice it also inverts the signal. When idle, the EIA-232 output should be "marking time," or at a negative voltage.

Your problem seems to be that the signal going to pin 5 is incorrect. It should sit at a high level, and pulse low when the K2 is transmitting data. Since it's low all the time, I would suspect a wiring problem (this single goes through the internal cable to the header connector which plugs into the control board.) Check for shorts to ground, or a lack of continuity from U1 pin 12 to header pin 3.

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