Specifications

Net-2000™ VCU Users Manual
Version 4.0, December, 2013
Interface Protocol
6.3.2.4 Channel Data Packet Bytes 0 and 1 (len)
The len parameter (bytes 0 and 1) hold the 16-bit length of the packet. The packet length is always 220 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
Data Packet Size 0 0 0 0 0 0 0 0 1 1 0 1 1 1 0 0 220 bytes
Table 13 len Header Parameter
6.3.2.5 Channel Data Packet Bytes 2 and 3 (type)
The type parameter (bytes 2 and 3) is 16-bits packet type and is always 0x0003 for channel data.
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
Channel Data 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0x0003
Table 14 type Header Parameter
6.3.2.6 Channel Data Packet Bytes 4 and 5 (seq)
Bytes 4 and 5 hold the 16-bit sequence number. 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 15 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.
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