Vega NB-12 / User Manual
11
Revision 05 of 21 January 2022
The device monitors status changes on the security inputs and when the security input
triggers, the device is activated and sends an alarm message to the network. The trigger
mechanism is configured through the program "Vega NB-IoT Configurator".
Security inputs can operate as pulse.
Equipment with NAMUR pulse output is not supported
CL+ and CL- contacts are used for connecting an external sensor with 4-20 mA
interface. Scheme for connecting is shown on the picture below.
PULSE INPUTS SETTINGS
When you connect the modem to metering devices with a pulse output, it is necessary
to consider the features of the pulse of a specific type of metering device: bounce, minimum
pulse and pause duration. To do this, it is necessary to record the characteristics of the pulse
with an oscilloscope or obtain information from the manufacturer of the meter.
The modem has a special software pulse filter. The filter is represented by two settings
for each pulse input (see section 4, “Settings” tab). Consider the features of filtering settings for
different pulse outputs.
1)
Mechanical pulse output
Usually, the mechanical pulse output in metering devices is implemented on a reed
switch, but it can also be a button or other mechanics. The main problem with such outputs is
contact bounce. At a moment of falling and rising, there are many additional impulses that need
to be no considered in the calculation. In addition, the pulse duration floats and depends on
the current flow rate of the meter. For correct counting, it is necessary to determine the
minimum useful pulse duration and the minimum pause between useful pulses (all that is less
is bounce). The obtained values must be set in the modem settings.
The minimum useful pulse duration is the pulse duration that the meter produces at the
maximum flow rate (the maximum flow rate is indicated in the meter's passport). This duration
does not include bounce time. The minimum pause duration can be set equal to the minimum