Chapter 7: Computer Link Function
(4)Guarantee of simultaneity
The cyclic transfer divides data into frames, depending on the amount of data being sent.
The
Note: When area 2 exceeds 3084 bytes, the
1Data transmission timing
When a node receives a request to send data from the upper layer, it copies its own cyclic data into a buffer and sends the data, one word after another. When the amount of data being sent is more than will fit in one frame, it divides the data in the buffer into multiple frames before sending.
2Refresh timing when receiving
After a node has received all the cyclic data from some other node, it will refresh the corresponding area while synchronizing with the upper layer.
When a cyclic data is sent as multiple frames, the receiving node will refresh the area after receiving all the frames from the other node. If any of the frames is missing, it will delete all the data from that node.
7
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On network |
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circuit | Cyclic data | ||
Data receiving side | Data receiving buffer | Group copy | |
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Common memory | Data receive |
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area |
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Guarantee of simultaneity of data