System Programming
HI 803 211 E Rev. 1.01.00 Page 73 of 110
6.1.3.2 Use of the Parameters Target Cycle Time and Target Cycle Time Mode
Using the settings for the Target Cycle Time Mode system parameter, the cycle time can be
maintained as constant as possible at the value of Target Cycle Time [ms]. To do this, the
system parameter must be set to a value > 0.
In doing so, HIQuad X limits reload and synchronization on the redundant modules to ensure
that the target cycle time is maintained.
The following table describes the settings for the Target Cycle Time Mode system parameter.
If a CPU cycle is shorter than the defined Target Cycle Time, the CPU cycle is
extended to the target cycle time.
If the CPU cycle takes longer than the target cycle time, the CPU resumes the cycle
without delay.
A reload or synchronization process is rejected if the reserve time is not
sufficient (target cycle time minus actual cycle time).
Similar to Fixed, but with the following differences:
1. To ensure that the synchronization process can be performed
successfully, the target cycle time may be violated for one CPU cycle.
2. To ensure that the reload can be performed successfully, the target
cycle time may be violated for 1 to n CPU cycles (where n is the
number of changed user programs).
The default setting is Fixed-tolerant!
After the first reload activation cycle, the values of watchdog time, target
cycle time and target cycle time mode apply in accordance with the new
configuration.
A maximum of every fifth cycle can be extended during the reload.
One single cycle may be extended during synchronization.
The CPU processes each CPU cycle as fast as possible. This corresponds
to a target cycle time of 0 ms.
A reload or synchronization process is rejected if the reserve time is not
sufficient (target cycle time minus actual cycle time).
A maximum of every fifth cycle can be extended during the reload.
One single cycle may be extended during synchronization.
Similar to Dynamic, but with the following differences:
1. If necessary, the target cycle time is automatically increased for one CPU
cycle to ensure that the synchronization process can be performed
successfully.
2. To ensure that the reload can be performed successfully, the target cycle
time may be automatically increased for 1 to n CPU cycles (where n is the
number of changed user programs).
After the first reload activation cycle, the values of watchdog time, target
cycle time and target cycle time mode apply in accordance with the new
configuration.
A reload or synchronization process is rejected if the reserve time is not
sufficient (target cycle time minus actual cycle time).
Table 25: Settings for Target Cycle Time Mode
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