I have a Bridgeport Powerpath 15 with Fanuc 21i-TB control. On it's setting screen it indicates channels (1~3) which are used for communication through RS232C. The machine is also equipped with PCMCIA slot located to the left of LCD. It accepts CF Cards but the manual says that we should select Channel 4 for reading through CF card but it is not shown on setting screen. Please tell me how we can activate channel 4 on the setting screen?