PK-88 OPERATING MANUAL
COMMAND SUMMARY
5 - 21
PK-88 - 96
CHDOUBLE
ON|OFF
Mnemonic:
CHD
Default: OFF
Parameters:
ON
Received CHSWITCH characters appear twice (doubled).
OFF
Received CHSWITCH characters appear once (not doubled).
CHDOUBLE displays received CHSWITCH characters as doubled characters.
In the following example CHDOUBLE is ON and CHSWITCH is set to '|':
|| this is a test.
The sending station actually transmitted:
| this is a test.
The same frame received with CHDOUBLE OFF would be displayed as:
| this is a test.
⇒
Set CHDOUBLE ON when operating with multiple connections to tell the difference between
CHSWITCH characters received from other stations and CHSWITCH characters generated by
your PK-88.
NOTE:
CHSWITCH characters must not be one of the channel numbers (0 to 9).
CHECK
n
Mnemonic:
CH
Default: 30
Parameters:
n
0 to 250 specifies the check time in ten-second intervals.
0
Zero disables this feature.
CHECK sets a timeout value for a packet connection, and depends on the setting of AX25L2V2.
Without the CHECK feature, if your PK-88 were linked or 'connected' to another station and the
other station seemed to 'disappear,' your PK-88 would remain in the connected state indefinitely,
refusing connections from other stations.
This might happen if propagation changes unexpectedly or an intermediate digipeater station fails
or is shut down while you and the distant station are connected 'via' that digipeater.
Your PK-88 tries to prevent this situation from occurring by sending a new connect request packet
when RELINK is ON and the specified time elapses without any packets being heard from the other
TNC.
If RELINK is ON, when a pre-Version 2 link is inactive for (CHECK times ten seconds), your PK-88
tries to save the link by starting a reconnect sequence. The PK-88 enters the 'connect in progress'
state and sends SABM (Connect Request) frames. In addition, the PK-88 adds a random time of up
to 30 seconds each time CHECK is used.
If AX25L2V2 is ON and packets have not been heard from the distant end for
n
times 10 sec-
onds, your PK-88 sends a 'check packet' to test if the link still exists to the other station.
The 'check' packet frame contains no information, but is interpreted by the distant station's TNC to
see if it is still connected. If the distant station's TNC is still connected, the distant station sends an
appropriate response packet.