Table of Contents
Advertisement
42
Logic function blocks
A memory is set when the input INPUT is set to 1. The output OUT then goes to 1.
When the time set T has elapsed, the memory is cleared and the output OUT goes to 0.
If a new pulse is obtained at the input INPUT before the time set T has elapsed, it does
not affect the timer. Only when the time set has elapsed and the output OUT is set to 0,
the pulse function can be restarted by the input INPUT going from 0 to 1. See time pulse
diagram, figure 19.
INPUT
OUT
0
1 1
2
3
)LJXUH ([DPSOH RI WLPH GLDJUDP IRU WKH SXOVH IXQFWLRQ ZLWK SUHVHW SXOVH OHQJWK 7
V
([FOXVLYH 25 ;25
The function block exclusive OR (XOR) is used to generate combinatory expressions
with boolean variables. XOR (figure 20) has two inputs, designated XOnn-INPUTm,
where nn presents the serial number of the block, and m presents the serial number of
the inputs in the block. Each XOR circuit has two outputs, XOnn-OUT and XOnn-
NOUT (inverted). The output signal (OUT) is 1 if the input signals are different and 0
if they are equal.
T=3s
4
5
6
7
8
xx00000571.vsd
&RPPRQ IXQFWLRQV
1
0
1
0
9
10
&KDSWHU
Advertisement
Table of Contents
