AEA PAKRATT PK-232, Technical Reference Manual

Page: 51 / 101

PK-232 TECHNICAL MANUAL APPENDIX A – AX.25 LEVEL 2 PROTOCOL
PK232TM Rev. A 5/87 A-6 Page 51
Fig. 3A – Nonrepeater AX.25 frame
Octet ASCII Bin. Data Hex Data
Flag 01111110 7E
A1 K
10010110
96
A2 8 01110000 70
A3 M
10011010
9A
A4 M 10011010 9A
A5 O 10011110 9E
A6 space 01000000 40
A7 SSID 11100000 E0
A8 W 10101110 AE
A9 B 10000100 84
A10 4 01100100 68
A11 J 10010100 94
A12 F 10001100 8C
A13 I 10010010 92
A14 SSID 01100001 61
Control I 00111110 3E
PID none 11110000 F0
FCS part 1 xxxxxxxx HH
FCS part 2 xxxxxxxx HH
Flag 01111110 7E
Bit position 76543210
The frame shown is an I frame, not going through a level 2 repeater, from WB4JFI (SSID=0) to
K8MMO (SSID=0), with no level 3 protocol. The P/F bit is set; the receive sequence number (N(R))
is 1; the send sequence number (N(S)) is 7.
A.2.13.1.1 Destination Subfield Encoding
Fig. 3 shows how an amateur call sign is placed in the destination address subfield, occupying oc-
tets A1 thru A7.
Fig. 3 – Destination Field Encoding
Octet ASCII Bin. Data Hex Data
A1 W 10101110 AE
A2 B 10000100 84
A3 4 01101000 68
A4 J 10010100 94
A5 F 10001100 8C
A6 I
10010010
92
A7 SSID CRRSSID0
Bit Position
76543210
Where:
1. The top octet (A1) is the first octet sent, with bit 0 of each octet being the first bit sent, and
bit 7 being the last bit sent.
2. The first (low-order or bit 0) bit of each octet is the HDLC address extension bit, which is set to
zero on all but the last octet in the address field, where it is set to one.
3. The bits marked "r" are reserved bits. They may be used in an agreed-upon manner in individ-
ual networks. When not implemented, they should be set to one.