Doc: ps2001-5-1101-001 Rev: R02. 00
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1486357009-URS, URS
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- Data structures
- 4.8.2 Data blocks
| 4.8 Data requirements (1) A formal structure must be established to ensure a common approach to the storage of data within the control system. This shall consider the following points • Establish a common approach to the handling of data, such that all modules do things, and store things in a consistent and familiar fashion • Store configuration (fixed/unchanging) data separately to dynamic (live/changing) data, such that the configuration data can be verified against a controlled and accurate copy of the software • Establish mechanism for passing global and common data to modules • Establish naming conventions for the various different types of data 60-71 Doc PS Rev Rb Data structures (1) User data structure (UDTs) may be used wherever required, including being passed as parameters into software modules. (2) Where UDTs are used, they will be fully documented and commented with all fields variables c) within the UDT being fully explained. (3) The Controller itself has various system data structures and these may be used as required (or specified) by the system blocks. 4.8.2 Data blocks (1) Data blocks will be the preferred mechanism for data storage (as opposed to using the internal memory bits within the Controller data blocks provide much greater storage capacity for data storage (essentially only limited by the memory capacity of the CPU) and are more flexible and provide better structuring of data than memory bits. (2) The use of instance data blocks 22 (iDBs) will be permitted in the normal manner required by TIA Portal and the Controller i.e. it is perfectly acceptable to use instance data blocks. (3) Data blocks that store configuration (fixed/unchanging) data will be separate to data blocks that hold dynamic (live/changing) data (for verification purposes) (4) The system will make allowances for recipe data that can be loaded from some other storage mechanism (a supervisory recipe handling system for example. Download 1.5 Mb. Share with your friends:
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