Begin the Application Download
Use the command to begin the download.
If the PLC is configured with a pre-existing application (the “old application”), it is invalidated at the beginning of the new application download. If the old application includes configured devices, the PAC closes the connections to those devices.
End of Application Download
The CIP Safety configuration is written to the CPU CIP Safety Stack (CSS), which computes a Connection Parameter CRC (CPCRC) for each connection. Next, each CSS computed CPCRC is compared with the corresponding CPCRC stored in configuration and calculated by the target DTM. In the event of:
CPCRC mismatch, the CSS rejects the application, and the PAC remains in NOCONF state.
Equality:
The CPCRC and connection parameters values are copied into the corresponding target DDDT.
The CSIO_HEALTH parameter inside the CPU DDDT (T_BMEP58_ECPU_EXT) is set to 0.
The CIP Safety target device DDDT HEALTH bits are set to 0.
The PAC opens the connections of configured devices via Type 2 SafetyOpen Requests
In the case of a CPCRC mismatch, the CSS rejects the application, and the PAC remains in NOCONF state.
Recalculation of the Safety Application ID
The safety application ID (SAId) is a signature of the safe part of the Control Expert application. It is stored as system word %SW169. The CSS computes a CRC on all instances of CPCRC. This CRC is added to the calculation of the SAId. Thus, a modification to the configuration of a CIP Safety target configuration changes the SAId value.