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CheckDataSetCRC and CheckFileCRC inputs

State-controlled inputs for activating the checksum validation of the

These validations help ensure that exactly the right data set is read.

If activated, the FB compares the respective CRC in the recipe file/data set to be read with the value applied to the corresponding CRC input (DataSetCRC, FileCRC).

Note
Independently of these configurable validations, the FB always checks the file/data set consistency by recalculating and comparing the file/data set CRC.

Data type: SAFEBOOL

Connection: Connect this input to a variable or constant

If the function block is activated (input Activate = TRUE), the possible values at this input lead to the following function block behavior:

ValueDescription
SAFETRUERequest to validate the respective CRC. Data is only considered as valid, if the read CRC is identical with the expected CRC.
SAFEFALSEData read from the recipe file is considered as valid without validating the respective CRC.

Observe the hazard message below this table.

WARNING
Non-conformance to safety function requirements
  • Make certain that appropriate procedures and measures (according to applicable sector standards) have been established to verify that the read recipe data set has not been modified or belongs to another safety application in case that the CRC validations are deactivated (SAFEFALSE value at the input(s) CheckDataSetCRC, CheckFileCRC, or CheckProjectCRC).
  • Include in your risk analysis the impact of reading wrong recipe data from a modified or wrong recipe file while the CRC validations are deactivated.
  • Validate the overall safety-related function with regard to possible impact of reading data from a modified or wrong recipe file while the CRC validations are deactivated.