Epson Multi-mode Data Controller MFJ-1278B Benutzerhandbuch

This signal is used for transmitter activation.  The SIO will pull this output low when the 
MFJ-1278B wants to transmit; otherwise it will remain high.  This pin is normally jumpered 
to pin 6 when the on-board modem is used. 
 
Pin 6 Transmitter Key Input 

This signal is an input to the on-board modem.  It activates the PTT pin of the radio 
connector via the watch-dog timer.  It should be left high and pulled low only when 
transmission is desired.  This pin is normally jumpered to pin 5 when the on-board modem is 
used. 
 
Pin 7 CONNECT Status Output 

This pin is an output from the SIO.  It is normally low and goes high only when the MFJ-
1278B is in the connected (error-free) mode with another packet station.  Its status is 
monitored via the CON LED. 
 
Pin 8 Unacknowledged Packets Pending Status Output 

This pin is an output from the SIO.  It is normally low and goes high only when this MFJ-
1278B has unacknowledged packets in its transmit buffer.  Its status is monitored via the STA 
LED. 
 
Pin 9 CTS Input 

This pin is an input to the SIO.  It is high when the attached modem is not ready to accept 
data, and low when the attached modem is ready to accept data.  The TNC will not attempt to 
send data when this pin is high.  This pin is normally jumpered to pin 10 when the on-board 
modem is used. 
 
Pin 10 Transmitter Key Input 
This pin is physically tied to pin 6, above.  It is      used in conjunction with pin 9, above to 
allow the MFJ- 1278B to use the on-board modem whenever the transmitter  is activated. 

 
Pin 11 Transmitter Clock (16x) Input 

This pin is tied to the NRZ-to-NRZI converter, which expects a clock signal at 16 times the 
desired radio port data rate, e.g., 4800 Hz for 300 baud.  This pin is normally jumpered to pin 
12 when the on-board modem is used. 
 
Pin 12 Transmitter Clock (16x) Output 

This pin is tied to the radio baud rate switch network.  It provides a clock at 16 times the