INTRO
4
corresponds to a setting of Full Duplex for the computer. If you set your computer for Half Duplex,
you will need to turn ECHO OFF or you will see two of everything you type. When using a split
screen program, you may want to set ECHO OFF in the TNC because the program will be handling
what you type in the buffered keyboard screen.
Flow Control
. Often times one device may talk to another device faster than it can handle the in-
formation. When this happens, the excess information is stored in a buffer until it can be pro-
cessed. This buffer is only so large. If the data were to over-flow the buffer, it would be lost. Flow
Control is the terminology used for how the devices inform each other to stop or start sending da-
ta. There are two ways to accomplish this: software and hardware. The TNCs default XFLOW ON
allows the TNC to implement software flow control (hardware flow control is always recognized by
the TNC).
Software Flow Control is implemented by the program or TNC looking at the data and watching for
two certain characters. One of these characters (normally Ctrl-S) tells the device to stop sending
data and the other (normally Ctrl-Q) tells the device to re-start sending data. The TNC commands
XOFF and XON tells the TNC which characters to send to the computer to stop and start data flow.
The commands STOP and START define which characters the TNC expects from the computer.
These commands all come defaulted for normal software flow control.
Hardware Flow Control is implemented by the device watching the voltages on the RTS and CTS
pins of the RS-232 port. The TNC will always monitor these pins, so only connect them if you are
going to use them. If you use hardware flow control, you should turn XFLOW OFF. See the Con-
necting your Computer section of the Installation Manual for how to wire your RS-232 cable for
hardware flow control.
Perm
. If you would like to customize the defaults in the TNC for your situation, all you have to do
is type
PERM
at the
cmd:
prompt (followed by a RETURN or ENTER key). This command will write
your customized defaults to the EEPROM. Now, if you turn the TNC off and back on again, your de-
faults will be used. This command can be used at least 1000 times, so as you experiment with
your parameters and find ones you would like to have different than factory default, just use this
command. If for any reason you ever want to go back to the factory default, a Hard Reset can be
performed (see the Hard Reset section of the Installation Manual), or use the
RESTORE D
com-
mand as described in the Commands Manual.
Dual-Port Set-Up Commands
PORT
. The
KAM
and
KPC-4
both have two radio ports. When turned on, the
KAM
will be address-
ing the VHF port and the
KPC-4
will address Port 1. If you wish, this may be changed so that the
other port will be addressed when the unit is turned on. For the
KAM
, you could type
PORT HF
at
the
cmd:
prompt, and for the
KPC-4
you would type
PORT 2
. This command would then need to
be PERMed (if not using Battery Backup or SmartWatch). This only affects what port the TNC will
address when it is turned on after the next soft reset. In order to change ports during Packet oper-
ations see Multi-Connects in the Packet section or the STREAMSW command in the Commands
Manual. When using non-packet modes on the
KAM
the HF port is automatically selected. In order
to enter a non-packet mode, the MAXUSERS command must be set to allow HF operation.
MAXUSERS
. This command causes the TNC to allocate the memory required for the maximum
number of simultaneous connections you wish to allow. The
KAM
and
KPC-4
will allow a setting of
0. If MAXUSERS is set to 0/0, these TNCs will accept only one connect at a time from either port of
the TNC. This special condition will be highlighted by being displayed simply as MAXUSERS 0. This
makes it feasible to use the
KAM
/
KPC-4
with MBL or RLI BBS programs on two frequencies. Setting
MAXUSERS to 0/n or n/0 will disable the port designated for 0.