RS-232 data TAP with AccelePort Xem

Hi,
I’m trying to monitor my rs-232 device with an Y. My device is using the Transmit (2), received (3) and SG (7) - db25. I’m using the BlackBox FA140A (DB25 Femele connector). I have 2 computer with 1 Acceleport Xem (16 ports, pci card ) connected on each ( one for received the data from my device and the other one for monitor the rs-232 ). The monitoring computer use only the “receive” and “SG”. When both computer have power up, everything is fine, I can monitor my rs-232 device and the other computer can receive the data from my rs-232 device. When I power down the monitoring computer, everthing stop! The only way to resolve the problem is to disconnect the cable from the Accelport Xem from the monitoring computer. I don’t have the problem is I connect the cable on the built-in com port of the monitoring computer. Seem that its a voltage issue… any idea???
Thanks!!!

These products are powered from the host system bus, so you are likely looking at a power issue depending on the state of the host server.

For this type of application, you might want to consider an ethernet based product line, such as the PortServer TS.