P4033¶

Code: P4033
Message: Partial-access syntax (.%Xn) requires –allow-partial-access-syntax flag

This error occurs when a source uses the IEC 61131-3:2013 partial-access bit syntax (.%Xn) without enabling it. Partial-access syntax is standardized in Edition 3 of IEC 61131-3 but is not part of Edition 2, so it is gated behind the --allow-partial-access-syntax flag (also enabled by the rusty and iec61131-3-ed3 dialect presets).

Example¶

The following code will generate error P4033:

PROGRAM main
VAR
    b : BYTE;
    r : BOOL;
END_VAR
    r := b.%X0;
END_PROGRAM

To fix this error, either use the Edition 2 short form .n:

r := b.0;

Or enable partial-access syntax with one of:

--allow-partial-access-syntax
--dialect=iec61131-3-ed3
--dialect=rusty

Scope¶

IEC 61131-3:2013 defines partial access at five granularities — .%Xn (bit), .%Bn (byte), .%Wn (word), .%Dn (double word), and .%Ln (long word). IronPLC currently implements only the bit form .%Xn behind this flag. The wider forms are recognized as partial-access syntax and therefore also raise P4033 when the flag is off; they are not yet accepted when the flag is on and still produce a lexer error there. See Bit Access for the full feature description and current support status.