Creating A Schedule - rotork Mk3 Technical Manual

Foundation Fieldbus CP Option Card Technical Manual
7.1

Creating a schedule

In order to use any Function Block, with the exception of the Resource Block and the Transducer
Block, the required blocks must be placed in a 'Function Block Application' using a suitable
configuration tool. This ensures the blocks are processed by the LAS in the correct way, allowing
them to publish data when required. Note that blocks do not have to be interconnected at this stage.
Once a control strategy has been worked out, the individual function blocks for all network devices
distributed across the network can be interconnected using the DCS or a configuration tool. The
configuration process also includes formatting the schedule for the execution of the function blocks.
Many configuration tools include the facility to create and alter the schedule, which is downloaded to
the system by the host or configuration system.
The individual function blocks each require a time slice of the total execution cycle in which to operate.
The execution times required for each block type in the FF CP card are as indicated in the table:
Note:
1. When constructing an application with interconnected function blocks it is recommended
by the Foundation that at least 50% of the total cycle time is left free to allow for the
background bus activities to be performed. Failure to follow this guideline may result in the
incorrect functioning of the downloaded schedule.
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Function Block
Analogue Input (AI)
Analogue Output (AO)
Digital Input (DI)
Digital Output (DO)
Controller (PID)
Controller (CS)
Publication PUB089-005-00_0618
Execution Time (mSec)
50
50
50
50
100
50