Siemens simatic S7-1500 Manual page 22

Parameters/address space
4.3 Address space
Value status (Quality Information, QI)
The meaning of the value status depends on the submodule on which it occurs.
For the first submodule (=basic submodule), the value status 0 indicates that the value is
incorrect or that the IO controller of the basic submodule is in STOP state.
For 2nd to 4th submodule (=MSO submodule), the value status 0 indicates that the value is
incorrect or one of the following errors has occurred:
● The basic submodule is not yet configured (not ready).
● The connection between the IO controller and the basic submodule has been interrupted.
● The IO controller of the basic submodule is in STOP or POWER OFF state.
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Digital output module DQ 32x24VDC/0.5A HF (6ES7522-1BL01-0AB0)
Manual, 09/2016, A5E35683508-AB