With RsKey resident, an application program has the 2 input sources, viz., the keyboard and a device connected to RS232c port. If both the key-board and an external device are active at the same time and they send data to the program at the same time, data from them will be mixed up in a receiving application program.
Since RsKey is forcing the foreground application to receive data from RS232c port where it does not have native support to discriminate the input sources, it is RsKey's responsibility to shoulder the burden to eliminate this possibility.
RsKey circumvents this problem by sitting between the data traffic from the keyboard and from RS232c. When the keyboard entry is under way, RsKey will hold data from RS232c and permit the keyboard to be the sole input source to the foreground application program. Once it starts receiving data from RS232c, the keyboard is disabled.
By setting an option, however, RsKey can give the keyboard a permanent priority over RS232c. Thus, even when RS232c is the current input source, a key press can occasion an input source switch to the keyboard.