Siemens SIMATIC S7-1500 System Manual page 98

Direct I/O access to the inputs and outputs of the module
In the case of the S7-1500 you still have direct read and write access to the I/O, as an
alternative to access via the process image, if this direct access is required for programming
reasons.
Reference
Additional information on process image partitions is available found in the function manual,
Cycle and response times (http://support.automation.siemens.com/WW/view/en/59193558).
S7-1500 Automation System
System Manual, 02/2014, A5E03461182-AB
7.2 Process images and process image partitions
Configuring
97