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Parameter Definition / CRC Calculation
7.2 F-Parameters
The F-Parameters are already preconfigured with meaningful values in the default
setting and should only be changed if expressly required by the automation task. A
CRC which is automatically calculated by the SIMATIC Manager is necessary for
safe transmission of the individually set F-Parameters. This checksum corresponds to
the F-Parameter F_Par_CRC, which is displayed as a hexadecimal value in the
Properties – DP slave window under the heading Current F parameter
CRC (CRC1) when configuring the measuring system with the hardware configurator:
The value A9C3 entered in the example below is valid for the default setting shown
here, also see chapter "Setting the F-Parameters" on page 175.
7.2.1 Non-settable F-Parameters
The F-Parameters specified below are either managed by the measuring system or by
the F-Host, and therefore cannot be manually changed:
● F_Check_SeqNr: NoCheck
● F_CRC_Length: 3-Byte-CRC
● F_Block_ID: 1
● F_Par_Version: V2-mode
● F_Source_Add: 2002 (example value, is predefined by the F-Host)
7.2.2 Settable F-Parameters
It is assumed that the following parameters are configured with their standard values:
● F_SIL: SIL3
● F_Dest_Add: 503 (corresponds to the set PROFIBUS address +500)
● F_WD_Time: 125
● F_iPar_CRC: 1132081116 (calculation by means of TR tool TR_iParameter)
Each parameter change gives a new F_Par_CRC value, which is displayed as shown
above. If a safety program is already present, it must be re-generated.
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05/25/2011 TR - ECE - BA - DGB - 0079 - 03 Page 161 of 207