Chapter 15: Appendix
[5]
(1)Basic functions
The status of each node is monitored by the management table which each node keeps for itself. This table handles the data used to control each node participating in the network. The operation is outlined below.
When starting, it receives a token frame and refreshes the participating node management table and network management table.
Each node refreshes its own participating node management table when it receives a token frame.
Renews the participating node management table when receiving a participation request frame of a new entry.
Delete any node that does not send a token frame or which times out three times in a row.
(2)Control data
The participating node management table contains data related to the nodes currently participating in the network.
Participating node management table
Item | Number | Description | |
of bytes | |||
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Node number | 1 byte | 1 to 254 | |
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Upper layer status | 2 bytes | RUN/STOP/ALARM/WARNING/NORMAL | |
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Area 1 of common memory: Data top address | 2 bytes | Word address (0 to 0x1ff) | |
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Area 1 of common memory: Data size | 2 bytes | Size (0 to 0x1ff) | |
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Area 2 of common memory: Data top address | 2 bytes | Word address (0 to 0x1fff) | |
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Area 2 of common memory: Data size | 2 bytes | Size (0 to 0x1fff) | |
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Allowable refresh cycle time | 2 bytes | In units of 1 msec. | |
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Token monitor time | 1 byte | In units of 1 msec. | |
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Minimum separation of frames | 1 byte | In units of 100 µsec. | |
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Link status | 1 byte | Participate/leave | |
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- "0x1ff" is the hexadecimal notation for 1FF(HEX).
Note: This information is contained in the token frame received.
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