OFC represents ouptut flow control. IFC represents input flow control. When either of these are shown high or solid it indicates that a buffer overflow has occured on either the attached device (OFC) or the Digi serial port (IFC).
Cause: There is a flow control setting mis-match or mis-wired cabling causing the respective devices buffer to overflow.
Solution: Match up the flow control settings between those configured on the Digi port and those configured on the attached device.
For example if software flow control is being used, confirm the xon and xoff settings are applied on both sides of the serial link. Software flow control can be easily tested by attaching a PC or dumb terminal to the Digi serial port, send a large amount of data and press [Ctrl]-s and [Ctrl]-q to stop and start the flow of data.
For hardware flow control, the hardware flow control signal that is used on the attached serial device, must be attached to the CTS signal on the Digi serial port and CTS flow will need to be configured for the Digi serial port (either on the host with the driver installed or the Dig unit itself).