Entry type: Manual, Entry ID: 109756485, Entry date: 06/18/2018
SIMATIC Process Control System PCS 7 Compendium Part A - Configuration Guidelines (V9.0)
|Document:||Compendium Part A - Configuration Guidelines (V9.0) (03/2018, English)|
|Type of topic:||Fact|
In PCS 7, user-specific blocks can be created quite easily, meaning that particular customer requirements can be met in a very flexible way. A user-defined block has a faceplate and its block icon for operating and monitoring the OS.
Be sure to always factor in the corresponding expertise, time and effort for the creation, maintenance and upkeep of your own blocks. Working with existing PCS 7 block libraries is recommended with this. A major advantage with the existing library blocks is the fact that they are serviced and maintained systematically, including with regard to different PCS 7 versions. Project teams can save time and cost as a result, particularly for future upgrades where the original project team may no longer be available.
Criteria to consider when making decisions about creating user-defined blocks
The following points must be reviewed before creating user-defined blocks:
- What functions do any existing PCS 7 block libraries offer (e.g. PCS 7 add-on catalog) in terms of meeting your requirements?
- Does a sector-specific library already exist that covers your requirements?
- Can an existing PCS 7 block library be adapted to meet your requirements, e.g. related to the display?
- Is just one block to be created, or several blocks?
- Is there a description or specification of the functions required of the blocks to be created?
- Can user-defined blocks be maintained and serviced in the future?
Guidelines on the range of numbers
The block number range for AS blocks 0 to 2499 is already allocated for the standard, add-on and sector-specific libraries. The FB range of numbers is therefore divided up as follows:
- Up to FB1000: Allocated with existing PCS 7 block libraries
- FB 1800-1999: Reserved for the PCS 7 system
- FB 1025 and above: Provided for SFC types
- FB 2000- 2014: Allocation for the SIMOCODE Pro library
To avoid any conflicts with the number ranges of existing AS blocks, assign block numbers starting from 2500 when creating your own blocks.
Please note that the following CPU types do not support a block range of numbers greater than 2048:
Numbers in the range from 1200 to 1249 are recommended when using user-defined blocks on these CPU types.
Guidelines on naming
The system has a limit of 16 characters for symbolic names for function blocks. However, a maximum of 8 characters is recommended on account of the display in the CFC Editor. Symbolic names with more than 8 characters are not displayed in full in the CFC Editor for summary reasons.
When determining symbolic names the first characters should be allocated with the block names in order to allow the function blocks to be uniquely assigned during the configuration phase. If you want to expand a symbolic name with additional information (e.g. company abbreviation) then place this at the end of the symbolic name.
The following example illustrates the naming guidelines:
- Block name: "CountOh"
- Symbolic name: "CountOh_Siemens"
- Display in the CFC Editor: "CountOh_"
Guidelines on creation
The "Compile chart as FB" function should not be used when using APL blocks to create user-defined blocks as the "S7_x" attributes are not supported for structures. S7 SCL is provided for creating the blocks in this case.
You can find detailed information on creating technological blocks according to the PCS 7 guidelines in the "PCS 7 - Programming Instructions for Blocks" manual.