HEIDENHAIN TNC 306 Technical Manual - Manual (Page 320)

7-30
TNC 416/TNC 406/TNC 306 Commands 3/2000
3.1.3 LOAD TWO'S COMPLEMENT (L–) L–
Abbreviation for the PLC-Editor: L– (LOAD MINUS)
Logic Byte/Word Double Constant
Execution time [µs] ---- 2.4/2.0 2.2 1.8
Number of bytes ---- 8 6 8
Operands: B, W, D, K
Operation:
The contents of the addressed Operand (B, W, D) or a Constant (K) are loaded into the Word
Accumulator as a two's complement. In addition, the Accumulator is filled, if necessary, according to
the sign bit. The two's complement allows negative numbers to be stored. i.e. a number loaded with
the L– command appears in the Accumulator with an inverted sign.
This command may only be used with Word execution.
Example:
The contents of Byte B5 is to be negated, added to Byte B6 and the result assigned to Byte B8.
Initial state: Byte B5 = 15 (dec)
Byte B6 = 20 (dec)
Byte B8 = ?
Line Instruction Accumulator contents Operand contents
Bit 31 . . . 15 7 0 7 0
... x x x x x x x x x x x x x x x x x x
1 L– B5 ... 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 1 (–15) (+15) 00001111
2 + B6 ... 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 (+ 5) (+20) 00010100
3 = B8 ... 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 (+ 5) (+5) 00000101
To aid understanding of this example, the contents of the Accumulator and operands are shown as
decimal values in parentheses.
Line 1: The contents of Byte B5 are loaded into the Accumulator and the sign of the value is
inverted.
Line 2: The contents of the Word Accumulator and Byte B6 are added.
Line 3: The result is assigned to Byte B8.