| Type | Function block |
| Description | The function block returns a constant string with the PHOENIX device certificate hierarchy. The PHOENIX device certificate hierarchy contains the root certificates in PEM-coded format. With the SEC_VERIFY_DEVICE_IDENTITY function block these certificates can be used to verify the identity of the device. The function block is executed with a rising edge at the EXECUTE input. The device certificate hierarchy is successfully written to the TRUSTED_CERTS output when DONE = TRUE. After successful execution of the function block, the TRUSTED_CERTS output remains unchanged. |
| Notes | Function blocks have to be instantiated. The instance name of the function block has to be declared in the 'Variables' table of the POU where the FB is going to be used. The instance name must be unique within the POU. |
| Parameters | Input
 EXECUTE
| Data type: | BOOL |
| Description: | The function block is executed with a rising edge at the input. |
Outputs
DONE
| Data type: | BOOL |
| Description: | Indicates whether the function block has been executed or not (TRUE=executed, FALSE=not executed). After successful execution, the device certificate hierarchy is available at the TRUSTED_CERTS output. |
TRUSTED_CERTS
| Data type: | SEC_PEM_CERTIFICATES |
| Description: | Provides a string with the root certificates in PEM-coded format. The certificates are used by the SEC_VERIFY_DEVICE_IDENTITY function block to verify the identity of the device. |
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Application example
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