bit from byte IEC61131-3

[hapetter]

Hi.

I use TwinCAT, but I guess its a general IEC61131-3 question.

So I have a Profibus slave with 16 digital input. I like to link this fysical channels to variables in my PLC program. The 16 digital input are given as 2xUSINT (2bytes)

So my question is:
How to get a bit from a byte? Read hexcode?

If you are familiar with TwinCAT:
Is it possible to link a boolean to a bit in an USINT in system manager? How?

Best Regards
hans

 

[L D[AR2P#0.0]]

Here's an example for word to bool;

(*
Converts word to Boolean
*)
FUNCTION_BLOCK FB_WordToBool
VAR_INPUT
bEnable:BOOL:=FALSE;
bByteSwap:BOOL:=FALSE;
wWord:WORD:=16#0;
END_VAR
VAR_OUTPUT
END_VAR
VAR_IN_OUT
bBit0:BOOL;
bBit1:BOOL;
bBit2:BOOL;
bBit3:BOOL;
bBit4:BOOL;
bBit5:BOOL;
bBit6:BOOL;
bBit7:BOOL;
bBit8:BOOL;
bBit9:BOOL;
bBit10:BOOL;
bBit11:BOOL;
bBit12:BOOL;
bBit13:BOOL;
bBit14:BOOL;
bBit15:BOOL;
END_VAR
VAR
END_VAR
(* @END_DECLARATION := '0' *)
IF(NOT bEnable) THEN
RETURN;
END_IF;
IF (NOT bByteSwap) THEN
bBit0:=wWord.0;
bBit1:=wWord.1;
bBit2:=wWord.2;
bBit3:=wWord.3;
bBit4:=wWord.4;
bBit5:=wWord.5;
bBit6:=wWord.6;
bBit7:=wWord.7;
bBit8:=wWord.8;
bBit9:=wWord.9;
bBit10:=wWord.10;
bBit11:=wWord.11;
bBit12:=wWord.12;
bBit13:=wWord.13;
bBit14:=wWord.14;
bBit15:=wWord.15;
ELSE
bBit0:=wWord.8;
bBit1:=wWord.9;
bBit2:=wWord.10;
bBit3:=wWord.11;
bBit4:=wWord.12;
bBit5:=wWord.13;
bBit6:=wWord.14;
bBit7:=wWord.15;
bBit8:=wWord.0;
bBit9:=wWord.1;
bBit10:=wWord.2;
bBit11:=wWord.3;
bBit12:=wWord.4;
bBit13:=wWord.5;
bBit14:=wWord.6;
bBit15:=wWord.7;
END_IF;
 
END_FUNCTION_BLOCK

 

[Peter Nachtwey]

A WORD is a collection of bits. One should be able to access a bit within a word by specifying WORD.BIT#