Fieldbus Controller 750-837, /02x-000, 750-838, /02x-000 |
• 87 |
Data Exchange |
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Example:
512 byte output variables are addressed word-wise with the Unsigned16 data type.
Addressing the 256 data words is in this case done with:
-index 0xA580, sub-index 1 to 255 and
-index 0xA581, sub-index 1.
Index: |
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Sub- |
Contents: |
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Description: |
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Index: |
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0 |
255 |
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number of output variable blocks |
0xA580 |
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1 |
D1 *) |
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1. output variable block |
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... |
... |
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... |
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255 |
D255 *) |
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255. output variable block |
0xA581 |
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0 |
1 |
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number of output variable blocks |
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1 |
D256 *) |
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256. output variable block |
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*) D1 = |
Data |
word output variable 1, D255 = |
Data word output variable 255, etc. |
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3.1.5.4.2 Absolute Addresses
The CPU has direct access to the bus terminal data through absolute addresses. Addressing begins with the address 0 both with inputs and outputs. The corresponding addresses for bits, bytes and double words (DWord) are derived from the word addresses.
The structure of the process image is described in chapter 3.1.4 "Process Image". Addressing is done in this structure.
Input data |
%IW0 |
word-orientated data |
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%IWn |
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%In+1 |
bit-orientated data |
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%In+m |
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Output data |
%QW0 |
word-orientated data |
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%QWn |
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%Qn+1 |
bit-orientated data |
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%Qn+m |
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3.1.5.4.3 Calculate Addresses
The word address is the basis for calculation (word).
Bit Address |
Word address .0 to .15 |
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Byte Address |
1st byte: |
2 x Word address |
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2nd byte: |
2 x Word address + 1 |
DWord Address |
lower section: Word address (even numbers) / 2 |
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upper section: Word address (odd numbers) / 2, rounded off |
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WAGO-I/O-SYSTEM 750
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