11.3 Pulse inputs VA and VB
The pulse inputs are physically placed on the plug-in modules and are well suited for the collection of pulses from
e.g. water meters with Reed switch output or water meters with electronic pulse output.
1 Water meter with Reed switch output
Pulse inputs VA and VB are bounce damped and therefore well suited for receiving signals from a Reed switch.
The Reed switch output often has a built-in resistance (Rr) in order to protect the Reed switch itself. Pulse inputs
VA and VB function with Rr values up to 10 kΩ.
2 Water meter with electronic pulse output
The pulse inputs are also well suited for receiving signals from a water meter with electronic pulse output of min.
30 ms. pulse duration. The pulse inputs must have a ”LOW” level of ≤ 0.4 V and a ”HIGH” level of ≥ 2.5 V. If the
electronic pulse output has a polarity safety, it should be fitted with a Schottky-diode, and a possible serial
resistor (Re) should be max.500 Ω.
The inputs are configured via the FF and GG codes as shown in the table in paragraph 3.6. In the absence of other
information from the customer the inputs will be configured as FF=24 and GG=24
(10 l/pulse). After delivery the
FF and GG codes can be changed by means of the PC program METERTOOL (see paragraph 14)
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