Here a link to the documentation.
Directly represented variables define access to inputs and outputs of the PLC via their absolute addresses.
An absolute address consists of:
They can also overlap
VAR_GLOBAL
someInput1 AT %I0.0 : BOOL;
someInput2 AT %I0.0 : BOOL; // warning, address of someInput2 overlaps address of someInput1
someInput3 AT %IW0 : INT; // warning, address of someInput3 overlaps address of someInput1
someOutput1 AT %Q0.0 : BOOL;
someOutput2 AT %Q0.0 : BOOL; // warning, address of someOutput2 overlaps address of someOutput1
END_VAR
You need to configure the IOSignals in a VAR_GLOBAL section within a CONFIGURATION
CONFIGURATION IoSignals
VAR_GLOBAL
S_3_manualON AT %I10.0 : BOOL;
P_3_conveyorsForward AT %Q10.5 : BOOL;
END_VAR
END_CONFIGURATION