- 554 -
Receiving “Cancel command”
Discarding of
“select command”
Cancel logic
“Remote-cancel”
Cancel logic
“Local-cancel”
Return to “Wait
for a command”
When Cancel is issued
from the remote-end
When Cancel is issued
from the local-end
Figure 3.1-3 Scheme “Cancel command”
Reception of “operate command”
Following successful completion of the “select command”, the control function is ready to
receive an “operate command” in order to control a device. The receipt of “operate command”
is divided into “Operate command ‘On’ (Closing)” and “Control command ‘Off’ (Open)”; each of
the two commands is carried out based upon its origin i.e. “Remote”, “Local”, and “PLC”. If the
“operate command” is completed, the “select command” can be released; then a new “Wait for
a command” stage can commence for receipt of a new “select command”.
Release of
“select command”
Return to “Wait
for a command”
Receiving “Operate command”
Operate logic
“Remote-On-control”
Operate logic
“Remote-OFF-control
”
Operate logic
“Local-On-control”
Operate logic
“Local-OFF-control”
Operate logic
“PLC-On-control”
Operate logic
“PLC-OFF-control”
Receiving “Select command”
Select logic
“Remote-OFF-control
”
Select logic
“Local-On-control”
Select logic
“Local-OFF-control”
Select logic
“PLC-On-control”
Select logic
“PLC-OFF-control”
Select logic
“Remote-On-control”
Figure 3.1-4 Scheme “Operate command”
(ii) Command reception in DIR mode
In DIR mode, issuing an “operate command” is possible without the reception of the “select
command”. Thus, the reception of an “operation command” only features in the control scheme†.
We shall see the DIR mode later.
†Note: We can encompass the operation of the “select command” being performed
internally in the control scheme. Thus, the user is not required to take account of
the reception of the “select command”.
To Next Page
Loading...
