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Duplex Operation of Loop Controllers Section 3-5
Example
If the CPU Unit cycle time is 40 ms, the minimum cycle time for all the Loop
Controller function blocks must be at least 200 ms (200 ms, 500 ms, 1 s, or
2s.)
If the CPU Unit's normal cycle time is longer than 1/5 of the minimum opera-
tion cycle for the Loop Controller function blocks, the error in the length of the
function block operation cycle will increase. The error will be up to one CPU
Unit cycle time longer.
Note If the CPU Unit's normal cycle time is longer than 30% of the minimum opera-
tion cycle for the Loop Controller's internal function blocks for 3 consecutive
cycles, Auxiliary Area bit A42409 (Operation Cycle Error) will be set to 1 (ON).
Monitor this flag from the CX-Process Tool system operation verification
screen and if it is reset to 1 (ON), then set the Loop Controller's operation
cycle to a minimum of 5 times the CPU Unit's normal cycle time.
Note If the cycle time is less than 20 ms, the cycle will be considered to last through
the next cycle time.
For example, if the cycle time is 11 ms, it will be treated as 22 ms.
Time until the Process-control Unit (CS1D-CPU@@P) Starts Operation
Time to Operation Start
for Active Loop
Controllers
When the Process-control CPU Unit (CS1D-CPU@@P) is used in DPL mode,
the active Loop Controller will start operation without waiting for duplex initial-
ization in the following circumstances (see note):
At power ON, when initialization switch is turned ON, at the start of opera-
tion, or when data is being transferred
However, the operation cycle will be temporarily extended by up to 2.1 sec-
onds during a period of up to 150 seconds
*1
after operation has started.
*1 Up to 120 seconds when the Run under Duplex initial option is set to Do
not automatically return to duplex operation in the PLC Setup in the CPU
Unit, and up to 150 seconds when the Run under Duplex initial option is
set to Automatically return to duplex operation.
Note Even when the Run under Duplex initial option in the PLC Setup in the CPU
Unit is set to the default (Automatically return to duplex operation, i.e., start
operation after duplex initialization), the active Loop Controller will start opera-
tion without waiting for duplex initialization.
Time to Operation Start
for Standby Loop
Controllers
When the Process-control CPU Unit (CS1D-CPU@@P) is used in DPL mode,
the standby Loop Controller will take up to 92 seconds before operation starts
(i.e., the time taken for duplex initialization). The DPL STATUS indicator on the
Duplex Unit will flash green for 150 seconds
*1
and then will switch to being lit
(green) at up to 2.1 seconds after that.
At power ON, when the initialization switch is turned ON, at the start of op-
eration, or when data is being transferred
*1 Up to 120 seconds when Run under Duplex initial option is set to Automat-
ically Return to duplex operation in the PLC Setup in the CPU Unit, and up
to 150 seconds when Run under Duplex initial option is set to Do not auto-
matically return to duplex operation.
Changes to LCB Load
Rate in Duplex and
Simplex Modes
The CS1D CPU Unit's cycle time and the Loop Controller’s LCB load rate are
different in duplex mode and simplex mode. Verify the system's operation in
both modes in trial operation before actually running the system.
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