Digital Voice Systems Net-2000-P25, Руководство пользователя

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Net-2000™ Voice Codec Unit
User’s Manual
Page 34
DVSI Confidential Proprietary
Section 4 – Net-2000™ VCU Interface Protocol
Nack Packet
The Nack packet is used to respond to badly formatted or unrecognized packets.
Ack Packet
Bytes
(msb-lsb)
Bit
7 6 5 4 3 2 1 0
Bit
7 6 5 4 3 2 1 0
Parameter Name
0 – 1 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 len
2 – 3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 type
H
e
a
d
e
r
4 – 5 x x x x x x x x x x x x x x x x seq
6 – 7 X x x x x x x x x x x x x x x x cmd
8 – 9 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 reason
Table 18 Nack Packet
Nack packets have the following format described Table 18 and C-language data structure below:
struct nack_packet_t {
short len;
short type;
short seq;
short cmd;
short reason;
};
The size of the Nack packet is ten bytes. The elements of the Nack packet are described in detail in
the following sections.