Siemens SIMATIC PCS 7 Operation And Maintenance page 56

Service and maintenance of SIMATIC PDM
6.3 Managing device descriptions in the project
Example for the list of devices integrated in the device catalog
Please be aware that your project may contain a device type which has different SW/FW
revisions. The EDD version must always match an SW/FW revision of the device. If an
incorrect EDD is assigned, PDM will detect the deviation and communication with the device
will not be established. As a user you will receive a message from PDM stating which device
it expects and which one it has detected during device identification.
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Compendium Part D - Operation and Maintenance (V9.0)
Operating Manual, 02/2018, A5E43228948-AA