5. Dual Function
69
:
OPC Server doesn’t support ths system has both of 1:1 backup and N:1 backup.
5.2 Dual state management
The states of OPC Server are described below.
1) INIT : Initializing
2) PRE-ONLINE: Wait for online (The talker is none.)
3) ONLINE: Reading scan data. The talker is only own node’s.
4) BACKUP: Reading scan data. The talkers are own node’s and parent node’s.
5) STANDBY: Reading scan data. The talker is none.
It is impossible to write the scan data.
6) STANDBY-LOCK: STANDBY state and locking
7) DOWN: Node down
Normally, the states of all nodes are “ONLINE” but when the system detects an error, the state
of abnormal node becomes “STANDBY”.
On “STANDBY” state, it is possible to read scan data normally but impossible to write it.
When the parent node and the child node are “ONLINE”, if the state of the parent node
becomes “STANDBY”, one of the own node becomes “BACKUP”.
On “BACKUP” state, it is possible to read scan data normally and the talker blocks of the
parent node are added to own.
At this time, OPC Clients must request the own node to write scan data..
(OPC Clients mustn’t request the parent node.)
TC-net 100
Ethernet
Client
nVCON
nVCON
nVCON
nVCON
Client
Client
(ST1)
(ST2)
…
… …
always read.
All tags can be
always read.
talker can be written.
To Next Page
Loading...
Need help?
General
