
Fieldbus Communications Support
Input and Output The application of the INTERBUS bit packing rules to the sample island assembly
Data Exchange results in four words of output data and five words of input data. The tables that follow show how digital data is bit packed for optimization, and how data, status, and echo output data (from outputs) appear in the PLC as the same data type (digital input data). In these tables, N refers to the island node number. That is, N1 represents the first addressable node (module) on the sample island bus, N2 the second, and so forth.
Output Data |
| The following table shows how the four words in the sample island assembly output | ||||||||||||||
Exchange |
| data process image are organized after applying the bit packing rules: |
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| Bit Number |
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Word | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
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1 | NIM control word |
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2 | empty (set to 0) |
| N6 output data |
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| N4 output data |
| N2 output | |||||||
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| data |
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3 | N8 (channel 1) analog output data |
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4 | N8 (channel 2) analog output data |
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Input Data |
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| The following table shows how the five words of the sample island assembly output | |||||||||||||||||
Exchange |
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| data process image are organized after applying the bit packing rules. The first word | |||||||||||||||||
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| contains the NIM status. |
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| Bit Number |
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Word | 15 | 14 | 13 | 12 | 11 | 10 |
| 9 | 8 | 7 |
| 6 | 5 | 4 | 3 |
| 2 | 1 | 0 | |
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1 | NIM status |
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2 | empty (set to 0) |
| N3 input data |
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| N2 output | N2 output | N1 input | N1 input | |||||||||||
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| status |
| echo |
| status |
| data |
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3 | empty (set to 0) |
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| N5 input data |
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4 | N7 (channel 1) analog input data |
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5 | N7 (channel 2) analog input data |
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40 | 890USE19600 April 2004 |