Specifications

Net-2000™ VCU Users Manual
Version 4.0, December, 2013
Interface Protocol
6.3.6 Nack Packet
The Nack packet is used to respond to badly formatted or unrecognized packets.
Nack Packet
16 bit Word
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Bytes
Byte (n) Byte (n+1)
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 1 type
Header
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 49 Nack Packet
Nack packets have the following format described Table 49 and C-language data structure below:
struct nack_packet_t {
short len;
short type;
short seq;
short cmd;
short reason;
};
Th
e size of the Nack packet is ten bytes. The elements of the Nack packet are described in detail in the following
sections.
6.3.6.1 Nack Packet Bytes 0 & 1 (len)
The len parameter (bytes 0 and 1) hold the 16-bit length of the packet (Table 50). The packet length is ten bytes.
len = Length (in bytes) of total packet (including header)
16 bit Word
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Byte 0 Byte 1 Decimal Value
Ack Packet Size 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 10 bytes
Table 50 len Header Parameter
(Subject to Change) Page 58
DVSI CONFIDENTIAL PROPRIETARY