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Byte Format
7-12 System Instrument Command Reference
Each byte sent with this command is expected to be in the following format:
Bit #
7
Control Bit
Control Bit is used to indicate the serial driver information such as clear,
reset, or end of transmission. This bit is ignored by the regular 488.2
driver. The control bit should be one for regular data.
Check Bits are used to detect and correct a single bit error. The control
bit is not included in the check. The check bits are a Hamming single bit
error correction code, as specified by the following table:
Data Value
Data bits are the actual data being transferred (four bits at a time). Each
word to be written requires four data bytes for transmission. The
significance of the data is dependant on the order received. The first data
byte received contains the most significant nibble of the 16 bit word to be
written (bits 15-12) . The next data byte received contains the least
significant nibble of the most significant byte of the word (bits 11-8). The
third data byte received contains the most significant nibble of the least
significant byte of the word (bits 7-4). The fourth data byte received
contains the least significant nibble of the least significant byte of the
word to be written (bits 3-0). Once all four bytes have been received the
word will be written.
6
5
4
Check Bits
Check Bits
0
0
1
7
2
6
3
1
4
5
5
2
6
3
7
4
8
3
9
4
10
5
11
2
12
6
13
1
14
0
15
7
3
2
1
0
Data Bits
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