Specifications

Net-2000™ VCU Users Manual
Version 4.0, December, 2013
Interface Protocol
6.3.6.2 Nack Packet Bytes 2 & 3 (type)
The type parameter (bytes 2 and 3) is 16-bits packet type and is always 0x0001 for nack packets.
type = Packet type
16 bit Word
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Byte 2 Byte 3
Hex Value
Nack 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0x0001
Table 51 type Header Parameter
6.3.6.3 Nack Packet Bytes 4 & 5 (seq)
Bytes 4 and 5 hold the 16-bit sequence number (see Table 52). The sequence number is used as a method to detect
if and when data packets are dropped, so it is important to ensure that consecutive sequence numbers are transmitted
for channel data packets during operation.
seq = Sequence number*
16 bit Word
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Byte 4 Byte 5 Decimal Value
Minimum Value 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 -32768
Maximum Value 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 32767
Table 52 seq Header Parameter
*Note: Sequence numbers should be incremented by one every time a packet is
transmitted. When the sequence number reaches 32767, the next valid sequence
number is -32768.
6.3.6.4 Nack Packet Bytes 6 & 7 (cmd)
The cmd element is used to indicate the packet type being Nack’ed.
cmd parameter
16 bit Word
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Packet Type Nack’ed
Byte 6 Byte 7 Hex Value
Type x x x x x x x x x x x x x x x x 0xXXXX
Table 53 cmd Parameter
(Subject to Change) Page 59
DVSI CONFIDENTIAL PROPRIETARY