Kramer Electronics Ltd.
VS-1616DN-EM
– Protocol 3000
151
Using the Packet Protocol
The packet protocol is designed to transfer large amounts of data, such as files, IR
commands, EDID data, etc.
To use the packet protocol:
1. Send a command, for example
LDEDID
2. Receive READY or ERR###
3. If READY:
•
Send a packet
•
Receive
OK
on the last packet
•
Receive
OK
for the command
4. Packet structure:
•
Packet ID (1, 2, 3…) (2 bytes in length)
•
Length (data 2 for CRC)
– (2 bytes in length)
•
Data (data length -2 bytes)
•
CRC - 2 bytes
01
02
03 04
05…
Packet ID Length
Data CRC
5. Response:
~
NNNN
SP
OK
CR LF
Where NNNN is the received packet ID in ASCII hex digits.
When calculating the CRC, the polynomial for the 16-bit CRC is:
CRC-CCITT: 0x1021 = x
16
+ x
12
+ x
5
+ 1
Initial value: 0000
Final XOR Value: 0
sanity-free.org/133/crc_16_ccitt_in_csharp.html
CRC example:
Data = “123456789”
Result => 0x31C3
