Instructions for Use
– SCHMIDT
®
Flow Sensor SS 20.700
Page 24
Figure 5-2 Position of LEDs for alternating flashing or moving light
Analog outputs
Switching characteristic Auto-U/I
Interval of load value R
L
Signaling mode
Signaling range
≤ 500 (550)
Current (I)
4 ... 20 mA
> 500 (550)
Voltage (U)
0 ... 10 V
Table 7
A hysteresis of approx. 50
Ω ensures a stable transition behavior (see
Figure 5-3
Depending on the provided output signal characteristic the accuracy of
detection of the switching point can be reduced. Therefore, it is recom-
mended to select the load resistance such that a safe detection can be
maintained (
≤ 300 Ω for current mode and ≥ 10 kΩ for voltage mode).
To detect possible alternating load in an actual zero signal (voltage
mode), the electronics generates test pulses that correspond to an ef-
fective value of approx. 1 mV. However, the latest measuring devices
may trigger in response to such a pulse in DC voltage measuring mode
and display short-term measuring values of up to 20 mV. In this case,
it is recommended to install an RC filter at the measuring input with a
time constant of 20 … 100 ms.
Error signaling
In current mode, the interface outputs 2 mA
23
.
In voltage mode, the output switches to 0 V.
23
In accordance with the Namur specification.
O1
I1
I2
O2
