![](/images/new-backgrounds/1264144/26414419x1.webp)
JBUS protocol (continued)
Function 3 and 4: read N words
The number of words must be less than or equal to the word field size (see memory board).
◗function 3: read output or internal words;
◗function 4: read input words.
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| slave address |
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| adress of |
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| number of |
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| first bit |
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| words |
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| response |
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| slave address |
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| number of |
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| first word |
| last word |
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| bytes read |
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| PF |
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example
Reading words at location 146 to 14B of slave at address 28H (voltage fields)
request: |
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28 | 03 |
| 0146 |
| 06 |
| A7 E0 |
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response: |
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28 | 03 |
| 0C |
| XXXX |
| YYYY | CRC 16 | ||
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word 0146 | word 014B |
Function 5: writing a bit
request
slave address | 5 |
| bit address | bit value |
| 0 | ||||||
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1 byte | 1 byte |
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| write 0 | |||
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| bit set to 1 |
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CRC 16
2 bytes
response
slave address
5
bit address
bit value
0
CRC 16
In function 5 the response and request frames are identical.
example
Setting bit location C05 to 1 of slave at address 40H (inverter on)
request:
40 05 0C05 FF 00 90 7A
Page 10 - 6739389EN/FB