HEIDENHAIN TNC 306 Technical Manual - Manual (Page 352)

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TNC 416/TNC 406/TNC 306 Commands 3/2000
3.5
Comparisons
3.5.1 EQUAL TO (==) ==
Abbreviation for the PLC-Editor: == (EQUAL)
Byte/Word/Double Constant
Execution time [µs] 1.8 to 2.4 2.0
Number of bytes 6 8
Operands: B, W, D, K
Operation:
With this command, a direct transfer from Word to Logic processing occurs. The contents of the
Word Accumulator and the contents of the addressed operand are compared. If the Word
Accumulator and the operand are equal, the condition is true and the Logic Accumulator is set to 1.
If they are not equal the Logic Accumulator is set to 0. The comparison takes place over the number
of bits corresponding to the operand, i.e. B = 8 bit, W = 16 bit and D = K = 32 bit.
Example:
A constant is to be compared with the contents of Double word D8. The result is then assigned to
Marker M500.
Initial state: Constant = 16 000
Double word D8 = 15 000
The Accumulator and operand contents are shown in decimal notation. The 10 bit wide Accumulator
allows the entry of the highest possible Accumulator contents (2 147 483 647).
Line Instruction Accumulator contents Operand contents
x x x x x x x x x x
1 L K16000 1 6 0 0 0
Bit 31 . . . 7 0
2 == D8 ... x x x x x x 0 x x x x x x x 1 5 0 0 0
3 = M500 ... x x x x x x 0 x x x x x x x 0
Line 1: The constant is loaded into the Accumulator.
Line 2: The contents of the Accumulator and the Double word D8 are compared
( Accumulator = Operand ? ).
As the condition is not fulfilled the Logic Accumulator is set to 0.
Line 3: The contents of the Logic Accumulator (The result of the comparison) are
assigned to Marker M500.