Digital Input; Pulse Count - Novus LogBox Wi-Fi Instruction Manual

5.2 DIGITAL INPUT

LogBox Wi-Fi has a Digital Input channel that can be configured for "Pulse Count", "Event Log", or even for "Logs Control" modes. This Digital
Input can be disabled.
Regardless of the function for which it will be used, you must configure the type of sensor output that will be connected to the input: PNP, NPN, or
Dry Contact (refer to chapter Installation
interest of the digital signal to generate the count, event, or start/end of logs: rising edge, falling edge, or both edges.
Relationship between Sensor Type, Sensor Status, and Logical Level obtained in LogBox Wi-Fi
Sensor Type
PNP
NPN
Dry Contact
For Dry Contact sensors, it is necessary to set a debounce time of at least 50 ms (sensor stabilization time / time in which the sensor must remain
in the state of interest for it to be considered valid). For PNP or NPN type sensors, if configured in "Pulse Count" mode, it is not necessary to set a
debounce time. However, if the digital input is configured for the "Event Log" or "Logs Control" modes, a minimum debounce of 50 ms is required to
prevent any noise from generating a false event. In the "Event Log" and "Logs Control" modes, events will be generated after the end of the
debounce time.

5.2.1 PULSE COUNT

By setting the Digital Input on the "Pulse Count" mode, it will be possible to count the number of pulses occurring within a period and to log the
average flow rate. LogBox Wi-Fi has a 16-bit register for accumulating the number of pulses within a given range and logging it in the memory.
Thus, at each log range, LogBox Wi-Fi captures the number of pulses and logs it in the memory, zeroing the register to accumulate the pulses for
the next interval.
If the sensor is a Dry Contact sensor type, the LogBox Wi-Fi will be able to count to 10 pulses per second. For PNP and NPN sensors, 2000
pulses per second. However, it is important to note that these pulses will accumulate within the log range. Thus, it is necessary to evaluate the
sensor maximum frequency so that it does not exceed 65535 counts (16 bits) within the log range and overflow the register that accumulates them.
If the maximum sensor frequency is 2 kHz, the LogBox Wi-Fi will accumulate 2000 pulses per second for up to 32 seconds. By exceeding this
range, the number of accumulated pulses will exceed 65535 counts, resulting in overflow in the accumulator register. For a sensor that can reach
2000 pulses per second, it is recommended that the log frequency be less than 32 seconds.
In typical applications, such as flow and volume measurement, simple pulse counting is not enough, being necessary to convert these pulses into a
flow unit. For this, one can select the desired flow unit and a conversion factor which will transform the number of pulses generated by the
connected transmitter in flow information. The pulse conversion logged in the range for the flow unit configured by the user will occur every time the
logged data is displayed.
To streamline the digital channel configuration in "Pulse Count" mode and the conversion to flow in the unit required, LogBox Wi-Fi provides the
following units of measure:
Flow Units
NOVUS AUTOMATION
to see how the sensors should be connected). In addition to that, it is necessary to select the edge of
Sensor State
Table 03 - Digital Input
l/s,
l/min,
l/h,
gal/s,
gal/min,
gal/h,
m³/s,
m³/min,
m³/h.
Table 04 – Units of Measure
Open
Closed
Open
Closed
Open
Closed
Logical Level
0
1
1
0
1
0
Sensor Units
pulses/l,
pulses/gal,
pulses/m³.
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