F218_DXNR

Redundant instruction

NOTE

This is a redundant instruction. It is replaced by: XOR

The function performs a bit-wise exclusive NOR operation on two 32-bit data items at inputs s1 and s2. The result of the instruction is returned at output d.

Parameters

Input

s1 (DWORD, DINT, UDINT, DATE, TOD, DT): 32-bit equivalent constant or 32-bit area
s2 (DWORD, DINT, UDINT, DATE, TOD, DT): 32-bit equivalent constant or 32-bit area

Output

d (DWORD, DINT, UDINT, DATE, TOD, DT): 32-bit area for storing XNR operation result

Remarks

Using this instruction you can check how many bits in the two 32-bit data items are the same. At each position in which the bits at inputs s1 and s2 match, a 1 is produced in the result.
The variables s1, s2 and d have to be of the same data type.

Truth table:

s1	s2	d
0	0	1
0	1	0
1	0	0
1	1	1

Error flags

sys_bIsEqual (turns to TRUE for one scan): if the result calculated (output d) is 0.