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4.4.3.Map Descriptor Example. 1 - Map Descriptor Basics
In this example the basics required for each consumer Map Descriptor are explained.
Map_Descriptor_Name, | Data_Array_Name, | Data_Array_Offset, | Function, | node_name, | Length, | ge_producerID, | ge_exchangeID |
A1, | DA_AI3, | 5, | Passive, | Node_A, | 1, | 0.0.0.1, | 1 |
Data processed | The first element | When you |
define Map | ||
by this Map | of data will be | Descriptors to |
Descriptor will | stored in the | consume EGD |
be stored in this | Data Array in | data they must |
array. | the 6th position | be passive. |
| (Array elements |
|
| are indexed |
|
| from zero.). |
|
The node name | This is the number | These |
ties the Map | of data elements | |
Descriptor to a | that will be | parameters are |
node which in | consumed from the | required but will |
turn ties the Map | message be | be explained in |
Descriptor to an | processed using this | the next |
adapter and a | Map Descriptor. | example. |
protocol. |
|
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4.4.4.Map Descriptor Example. 2 - A Simple Consumer Map Descriptor
Map_Descriptor_Name, | Data_Array_Name, | Data_Array_Offset, | Function, | node_name, | Length, |
| ge_producerID, | ge_exchangeID, | ge_Data_Type |
A1, | DA_AI3, | 0, | Passive, | Node_A, | 20, |
| 0.0.0.1, | 1, | Int |
This is the dot format ID of the producer. It is not the IP address of the producer's Ethernet node.
This value identifies the producing processor.
This and the exchangeID uniquely identify a produced data packet.
This is a numeric value assigned by the PLC programmer to identify a specific data exchange to be received by the consuming device (the FieldServer in this case). It must match the ID specified in the producer.
The data in the data packet will be treated as 16 bit (two byte) signed integers. As the length=20 a total of 40 bytes will be processed.
The type of the Data Array should be capable of storing signed integers in this example.
If you do not use this keyword then the driver will process the data as bytes.
The data type is more completely explained in section Appendix A.1
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