Air gap sensor
SDP110
9
When the hysteresis function is set, the set point [SP] and the reset point [rP] are defined. The
rP value must be lower than the SP value. The distance between SP and rP is at least 4 % of
the final value of the measuring range (= hysteresis). If only the set point is changed, the reset
point is changed automatically; the difference remains constant.
FE
FE
FH
HY
HY
t
Fno
Fnc
FL
1
0
1
0
1
Fig. 3: Window function
1:
Process value
t:
Time
FH:
Upper limit value
FL:
Lower limit value
HY:
Hysteresis
FE:
Window area
Fno:
Window function NO (normally open)
Fnc:
Window function NC (normally closed)
When set to the window function the upper limit value [FH] and the lower limit value [FL] are
defined. The distance between FH and FL is at least 4 % of the final value of the measuring
range. FH and FL have a fixed hysteresis of 0.25 % of the final value of the measuring range.
This helps keep the switching status of the output stable if the flow rate varies slightly.
7) and the final value of the measuring
range (
Ò
Technical data) must be observed when setting SP, rP, FL and FH.
The switching signal in case of a fault is adjustable:
•
[FOU] = On: The output switches ON in case of a fault.
•
[FOU] = OFF: The output switches OFF in case of a fault.
•
[FOU] = OU: The output switches ON (pressure measurement) /
The output switches OFF (distance measurement and flow measurement).
4.5 Analogue output
The unit provides an analogue signal of 4…20 mA proportional to the process value.
The measuring range is scalable:
•
[ASP] determines at which measured value the output signal is 4 mA.
•
[AEP] determines at which measured value the output signal is 20 mA.
Minimum distance between ASP and AEP = 20 % of the final value of the measuring range.
7) and the final value of the measuring
range (
Ò
Technical data) must be observed when setting AEP.
If the measured value is outside the measuring range or in the event of an internal error, the current
signal indicated in the following figure is provided.
For measured values outside the setting range or in case of a fault, messages are displayed (UL, OL,
Err, NoData).