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GFK-0467K Chapter 4 Series 90-30/20/Micro Instructions Set 4-51
4
XOR (WORD)
The Exclusive OR (XOR) function is used to compare each bit in bit string I1 with the
corresponding bit in string I2. If the bits are different, a 1 is placed in the corresponding position in
the output bit string.
Each scan that power is received, the function examines each bit in string I1 and the corresponding
bit in string I2, beginning at the least significant bit in each. For each two bits examined, if only
one is 1, then a 1 is placed in the corresponding location in bit string Q. The XOR function passes
power flow to the right whenever power is received.
If string I2 and output string Q begin at the same reference, a 1 placed in string I1 will cause the
corresponding bit in string I2 to alternate between 0 and 1, changing state with each scan as long as
power is received. Longer cycles can be programmed by pulsing the power flow to the function at
twice the desired rate of flashing; the power flow pulse should be one scan long (one-shot type coil
or self-resetting timer).
The XOR function is useful for quickly comparing two bit strings, or to blink a group of bits at the
rate of one ON state per two scans.
_____
| |
(enable) —| XOR
_
|— (ok)
| |
| WORD|
| |
(input parameter I1) —|I1 Q|— (output parameter Q)
| |
| |
| |
| |
(input parameter I2) —|I2 |
|_____|
Parameters:
Parameter Description
enable When the function is enabled, the operation is performed.
I1 I1 contains a constant or reference for the first word to be XORed.
I2 I2 contains a constant or reference for the second word to be XORed.
ok The ok output is energized whenever enable is energized.
Q Output Q contains the result of I1 XORed with I2.