
USER'S GUIDE
COMMAND SUMMARY
PK232UG Rev. B 9/86
6-27
129
CHECK
n
Mnemonic:
CH
Default: 30 (300 sec.)
Mode: Packet
Parameters:
n
-
0 to 250 specifies the check time in ten-second intervals.
0 (Zero) disables this feature.
CHECK
sets a time-out value for a packet connection and depends on the setting of AX25L2V2.
Without the
CHECK
feature, if your PK-232 were linked or "connected" to another station and the
other station seemed to "disappear", your PK-232 would remain connected 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-232 tries to prevent this sort of "lockup" from occurring by sending a new connect request
packet when the specified time elapses without any packets being heard from the other TNC.
If a pre-Version 2 link is inactive for (
CHECK
times 10 seconds), your PK-232 tries to save the link
by starting a reconnect sequence. The PK-232 enters the "connect in progress" state and sends
SABM (Connect Request) frames. In addition, the PK-232 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-232 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.
If your PK-232 initiates the "check" and does not get an answer after RETRY+1 attempts, your PK-
232 starts a reconnect sequence just as if you had typed the
CONNECT
command.
If
AX25L2V2
is OFF and the other station has nit been heard for
n
times 10 seconds, your PK-
232 does not test the link to the distant station; your PK-232 sends a reconnect packet just as
if you had typed the
CONNECT
command.
CHSWITCH
n
Mnemonic:
CHS
Default: $00
Mode: Packet
Parameters:
n
-
0 to $FF (0 to 255 decimal) specifies an ASCII character code.
CHSWITCH
selects the character used by both the PK-232 and the user to show that a new con-
nection channel is being addressed.
The character can be PASSed in Converse Mode. The character is always ignored as a user-initi-
ated channel switch in Transparent Mode; it just flows through as data.
The outgoing channel cannot be changed while active or "on-line" in Transparent Mode.
To switch channels,
ESCAPE
to Command Mode, then enter Converse Mode to use the
CHSWITCH
command.