A RealPort port that is not responding may be stuck in a state of flow control. Determine if your port and peripheral device are configured for software (XON/XOFF) or hardware flow control, then, check the status of the stuck port using the front panel LED display on the PortServer. If the OFC LED is lit, the port is waiting for a response from the device. This could be a restart character if software flow control is used, or an EIA-232 signal if hardware flow control is used.
To unlock a port if the OFC light is active on the port, and the port is configured for software flow control, try entering a <CTRL-Q> (standard XON restart character) from a terminal attached to the port.
To unlock a port if the OFC light is active on the port, and the port is configured for hardware flow control, the hardware flow control signal must be raised on the port. For example, if the port is configured for DTR flow control, the DTR signal of the device is normally tied to CTS on the port. The CTS signal must be active on the port for the port to function. If the device is not raising the flow control signal or if the port is not receiving the signal through the cable, the port will remain stuck in a flow control state.