Topic: DMD0246
Math Logical OR Operator
The Math Logical OR operator ( || ) indicates whether either operands is TRUE. A discrete operand is considered TRUE if it is ON; a numeric operand is considered TRUE if its value is non-zero.
The operands can be any mix of signed integers, unsigned integers, real (floating point) numbers or discrete values. They can be any numeric or discrete memory location, or any numeric or discrete structure member.
Traditional math precedence rules are used to solve the math expression, The use of parentheses to remove any ambiguity in the processing order is encouraged.
Refer to the examples below:
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Signed Integers: assume D1 = 0 and X0 = ON and X1 = OFF
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||
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C0 = X0 || X1 |
C0 = ON || OFF C0 = TRUE || FALSE
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Both operands are discrete memory locations.
The result is placed in a discrete memory location.
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C0 = (X0 || X1) || D1
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C0 = (ON || OFF) || (0) C0 = (TRUE || FALSE) || FALSE) C0 = ON
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Two operands are discrete memory locations, the third is an integer memory location.
The result is placed in a discrete memory location.
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D0 = X1 || D1
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D0 = OFF || OFF D0 = FALSE || FALSE
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One operand is a discrete memory location, the other is an integer memory location.
The result is placed in an integer memory location.
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Casting Numeric Values: assume X0 = ON and DLV2000 = 0x80
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||
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C0 = X0 && DLV2000:7
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C0 = ON || 1 C0 = TRUE || TRUE C0 = ON
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One operand is a discrete memory location, the other is using the 'bit pick' cast operator which will examine the ON/OFF status of the bit at the specified position in the specified value.
The result is placed in a discrete memory location.
DLV memory locations are 16-bit Unsigned used by external DirectLOGIC devices. In this example a remote DirectLOGIC CPU has written a value of 0x0080 into DLV2000. The :7 cast operator will examine the state of the 8th bit (bit positions are 0-based) of the value in DLV2000.
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See Also:
Logical OR
Related Topics: