Kantronics KAM, Руководство пользователя

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Chapter 7 - Commands and Messages
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slot time before trying to transmit with the same probability. If PERSIST is 255, the KAM will trans-
mit with a probability of one, meaning it will transmit immediately, which is the way all TNCs have
been working up to now. The persistence algorithm has been added on top of the DWAIT algo-
rithm. If you plan to use persistence as defined by the amateur TCP/IP protocols, you should con-
sider setting DWAIT to 0.
SLOTTIME n default 5
n can be any value from 0 to 255 specifying the amount of time in milliseconds between suc-
cessive tries of the persistence algorithm.
PRECAUTIONS
Again, the KISSMODE command listed above is used only in conjunction with a TCP/IP program
running on your computer. Obtain TCP/FP details from a TCP/IP group. In addition the operation of
the KAM is set to respond with a KISS mode program that is compatible with the TCP/IP - KISS in-
terface defined at the time of manufacture. It is anticipated that the "KISS" interface will not
change, but this is an area of development, so if you have any questions, ask!
Additionally, if you turn KISSMODE on, perm it ON, and perform a reset or power off-on again
sequence, you will not be able to return to standard Packet operation unless you perform a hard
reset or use the special KISS (off) command, see below. To avoid this occurrence, we suggest that
when you turn the KISSMODE on, don't perm it unless you really want it to stay that way. So,
when you perform a power off-on again sequence, the default value of KISSMODE (which will be
off) will take you back to regular packet operation.
Control of the RAW KAM Commands under KISS
Although removing the human interface and the AX.25 protocol from the KAM makes most
commands unnecessary (they are in the TCP/IP program), the KAM is still responsible for keying
the transmitter's PTT line and deferring to other activity on the radio channel. It is therefore neces-
sary to allow your computer under TCP/IP to control a few KAM parameters, namely TXD and the
persistence values.
In order to do this it is necessary to distinguish between command and data frames on the
computer/KAM link. This is done by defining the first byte of each asynchronous frame between
the computer and KAM as a command. The upper half of the command byte specifies the radio
channel; the lower half of the command byte specifies the command type. The following types are
defined in frames to the KAM as:
type function command
0 data frame rest of frame is data to be sent on the HDLC channel
1 TXDdelay second byte is transmitter keyup delay in 10 ms units
2 persistence second byte of frame is persistence parameter p
3 slottime second byte of frame is slot interval
5 fulldup full duplex if second byte is zero, on otherwise
255 leave KISS turn off KISS Mode in KAM
In addition, the following type is defined in frames coming from a KAM to the computer run-
ning the amateur TCP/IP:
0 data frame rest of frame is received data
Asynchronous Frame Format
How are these commands mentioned above sent to or received by the KAM running in KISS
Mode? The KAM simply converts between synchronous HDLC, spoken on the half duplex radio
channel, and a special asynchronous, full duplex frame format spoken between your computer run-
ning TCP/IP and itself. Every frame received on the HDLC link is passed intact to the computer