Digital Input; Pulse Count - Novus LogBox-BLE Instruction Manual

6.2 DIGITAL INPUT

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

6.2.1 PULSE COUNT

By setting the Digital Input for Pulse Count, it is possible to count the number of pulses occurring within a period and to log the average flow rate.
LogBox-BLE 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
interval, LogBox-BLE captures the number of pulses within that interval and logs it in the memory, zeroing the register to accumulate the pulses for
the next interval.
The LogBox-BLE is capable of counting up to 10 pulses per second if the sensor configured is Dry Contact type and 2000 pulses per second for
PNP and NPN sensor types. However, it is important to note that these pulses will accumulate within the log interval. Thus, it is necessary to
evaluate the sensor maximum frequency so that it does not exceed 65535 counts (16 bits) within the log interval and overflow the register that
accumulates the counts.
Ex.: If the maximum sensor frequency is 2 kHz, the LogBox-BLE will accumulate 2000 pulses per second for up to 32 seconds. Because, by
exceeding this interval, the number of accumulated pulses will exceed 65535 counts, resulting in overflow in the accumulator register. Thus, 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 that transforms the number of pulses generated by the connected
transmitter in flow information. The pulse conversion logged in the interval for the flow unit configured by the user will occur every time the logged
data is displayed.
To streamline the configuration of the digital channel in Pulse Count mode and the conversion to flow in the unit required for the user, LogBox-BLE
provides the following units of measure:
Flow Units
NOVUS AUTOMATION
Sensor State
Table 03 - Digital Input
l/s,
l/min,
l/h,
gal/s,
gal/min
gal/h,
m³/s,
m³/min,
m³/h
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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