Technologies Computer Driver Instruction Manual

FS-8700-114 DeviceNet Master Manual Page 15 of 15
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Appendix B.4. Understanding buffer types and Map Descriptor functions
The diagram below explains the data flows for both buffers when using the FieldServer as a DN
Master:
Note that for the Input buffer, the data is coming from the external DN Slave and is transferred into
the DN Master card’s internal input buffer. The Rdbc (Read Data Block Continuous) Map Descriptor
transfers the data from the card buffer into the FieldServer’s Data Array packing it correctly according
to the specified DeviceNet_Data_Type.
For the Output buffer, the data is written from the FieldServer’s Data Array by the WRBC function
Map Descriptor (Write Data Block Continuous) into the DN Master card’s internal output buffer from
where it is transferred across the DeviceNet network to the external DN Slave’s input buffer.
0
1
243
0 1
243
….
….
Card output buffer
Card input buffer
External DN Slave 01
DeviceNet
Network
0
1
243
0 1
243
….
….
Card output buffer
Card input buffer
External DN Slave 126
243
243
0 1
1
….
….
Card input buffer
DeviceNet Card
DN Master
WRBC Map Descriptor
Data Array
FieldServer
Data Array
0
Card output buffer
RDBC Map Descriptor
Note: The Node_Name determines to
which external DN Slave date will be
sent to or fetched from.
Appendix B.5. Accessing Parameter Data in Remote Slaves
The DeviceNet driver only supports IO data. To access parameter data on Slaves it is necessary to
refer to the Slave device's user manuals for information on how to map their parameter data to IO
data locations.