User manual for flow meter with pulse input SPI-94
6.3.1.
One threshold mode
Figure 6.5 presents the principle of relay outputs operation for one threshold mode, and
an example values of other parameters.
Description:
A, B, C, D
- points where measured signal exceeds border values (expected value ± allowed deviation)
B
ON
,
B
OFF
,
D
ON
,
D
OFF
- relays state changes moments: (for
“t on”
> 0,
“t oFF”
> 0)
t
A
,
t
B
,
t
C
,
t
D
-
time periods while input signal is in zone A or zone B
Figure 6.5.
Principle of LED/relay output operation for one threshold mode
Parameter
“SEt P”
sets a
threshold
of the relay, and parameter
“HYSt”
sets a
hysteresis
of the relay (Figure 6.5 a). The relay can change his state
only
when input value
exceeds (over or under)
border value
and
t
A
,t
B
,t
C
,t
D
times
(
Figure 6.5
) are bigger than the
time defined by parameters
“t on”
,
“t oFF”
and
“unit”
.
Border values
means values equal
threshold
+
hysteresis
and
threshold
-
hysteresis
respectively.
If
“t on”
and
“t oFF”
parameters
are set to “0”, then the relay state will be changed
as soon
as input value exceeds any of the
border values
(see points A and C, Figure 6.5 a,
b, c).
If values of
“t on”
or/and
“t oFF”
are positive, then relay state will be turned on if the
input value exceeds the
border values
and stay bigger (or lower) during at least
“t on”
(see points B
ON
, D
ON
, Figure 6.5 a, d, e). Similarly, the relay will be turned off if time
“t oFF”
elapse since the input signal value exceeds any of the
border values
(see points
B
OFF
, D
OFF
, Figure 6.5 a, d, e).
20
“SEt P”
parameter
(expected signal value)
“HYSt”
parameter
(allowed signal
deviation)
measured
signal
displayed value
time
time
time
A
B
C
D
relay state
(
modE
=
on
t on
= 0
t oFF
= 0)
relay state
(
modE
=
on
t on
> 0
t oFF
> 0)
t
A
t
B
t
C
t
D
B
ON
D
OFF
relay state
(
modE
=
oFF
t on
= 0
t oFF
= 0)
relay state
(
modE
=
oFF
t on
> 0
t oFF
> 0)
“t oFF”
parameter
“t on”
parameter
B
OFF
D
ON
time
time
closed
open
a)
b)
c)
d)
e)
open
closed
open
open
closed
closed
“t on”
parameter
“t oFF”
parameter
zone A
zone B
