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Byte Format Each byte sent with this command is expected to be in the following format:

Bit #

7

6

 

5

 

4

3

2

1

0

 

 

 

 

 

 

 

 

 

 

 

 

Control Bit

 

Check Bits

 

 

Data Bits

 

 

 

 

 

 

 

 

 

 

 

 

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

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

 

 

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.

7-12 System Instrument Command Reference

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Agilent Technologies 75000 SERIES B, E1301B, E1300B user manual DIAGnosticDOWNloadCHECked SADDress