I want to create and map custom boolean variable list to point to MCP23S17 input/output pins. Only what I figure out is this.

I have created global variable list like this:

VAR_GLOBAL
   in1:BOOL (MCP23S17.byInputsA.0);
   out1:BOOL (MCP23S17.byOutputsA.0);      
END_VAR

Then in POU's ST code this:

out1:=in1

Is this syntax ok? What is the "proper" way to create variable map list to mpc's pins ?

Thank you !

If you want something that works, it may not be exactly what you want but I would just instantiate the device in the globals, like so:

MCP1: MCP23S17;
in1: BOOL;
out1: BOOL;

and then use in the ST code of the POU like this:

in1:=MCP1.byInputsA.0;
out1 := in1;
MCP1.byOutputsA.0 := out1:

or this:

MCP1.byOutputsA.0 := MCP1.byInputsA.0;

Not sure if you can define like you want to in the globals somehow, but I could be wrong..

.....
My intention was to declare all inputs and outputs boolean variables in one (global) place, so I can use it on several POU's.
I know I can use this code MCP1.byOutputsA.0 := MCP1.byInputsA.0; but i'd like to use more meaningful input/output names.
However I still don't know is this

VAR_GLOBAL
   in1:BOOL (MCP23S17.byInputsA.0);
   out1:BOOL (MCP23S17.byOutputsA.0);      
END_VAR

correct or not ?