How to use BIT_TO_WORD and WORD_TO_BIT

PLCnext Engineer
1

Hello,
I am using ladder logic in PLCnext and I get error CILG0030 saying i cant use them since they are in the safety program section but I need to convert a word into its bits and some bits into a word. How can I do this without access to the BIT_TO_WORD and WORD_TO_BIT commands?

2

There are a few alternatives I can think of:
Use dot notation to get partial access to ANY_BIT variables
1. , like WORD variables.
2. Use the GET_BIT, SET_BIT and RESET_BIT functions on individual bits in the word.
3. If there will be a lot of these types of operations, you could write your own function to do the same thing as the Safety FBs.

3

, When I use dot notation for a word that is tied to my DI16/1 in a ST program, the bit values don’t change. I can see the value change from 16#0000 to 16#0100 (DI/1) in my program variables, but at the bit level in my ST it will stay FALSE.
IF xIODI.X0 THEN
xIODO.X0 := TRUE;
ELSE
xIODO.X0 := FALSE;
END_IF;

xIODI is tied to di-1 / ~DI16.
xIODO is tied to do-1 / ~DO16.
It works fine if I assign a Bool var directly to DI/1 and use that, but not when trying to access the bit val of a Word.
It seems to only be the DI Word that has an issue. If I use a bool val for DI/1 and leave the xIODO.X0, it will write a value to the bit of the DO word as I would expect.
IF xIODI_1 THEN
xIODO.X0 := TRUE;
ELSE
xIODO.X0 := FALSE;
END_IF;

Any ideas why this would be the case?

4

If xIODI = 16#0100
then
xIODI.X0 will be FALSE.
xIODI.X8 will be TRUE.
Does this explain what you’re seeing?