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Appendix A.2. The IO image header
The IO image header appears at the start of every block of image data that is transferred to or from the SlotServer to the Logix CPU. It consists of 4 items of data:
Offset into image |
| Item |
| Description |
data block |
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| The value specified under the Map Descriptor’s |
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| Protocol |
| Protocol_Type_ID field is transferred to the Logix CPU |
0 |
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| and can be used to decode the protocol. The same | |
| Type |
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| value has to be transferred back to the SlotServer to | |
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| indicate the protocol. |
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| This field is automatically filled in by the SlotServer if a |
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| Node |
| Node Status Data Array with the name |
1 |
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| SlotServerNodes is declared. Its value can be used in | |
| Status |
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| the Logix CPU to check the status of Nodes connected | |
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| to the SlotServer. |
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| Block |
| The number of the Data Array for which the IO image |
2 |
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| data is valid for, e.g. a block number of 1 will indicate | |
| Number |
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| the data is to or from DataArray_1 | |
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3 |
| Reserved | Not used | |
Appendix A.3. How to obtain Node Status from the SlotServer
By declaring the following Data Array, the Node Status field in the IO image header will be filled in with the Node Statuses of all Nodes declared on the SlotServer:
// Data Arrays |
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Data_Arrays |
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Data_Array_Name, | Data_Format, | Data_Array_Length, | Data_Array_Function |
SlotServerNodes, | Bit, | 256, | Node_Status |
Note: The Data Array Name must be as shown for this function to work correctly.
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