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Installation Manual LOGS50 EN_MI_090221
1.11 DIGITAL INPUTS
1.11.1. HARDWARE CONFIGURATION
LOGS50 loggers have up to 8 digital inputs numbered from 0 to 7. For each
input, two kinds of terminals are needed, one specific to each input and another
one common to all of them (GND).
By default, a digital input which is not connected is interpreted as a “0” logic. To
obtain a “1” logic, it is necessary to connect the input to the GND terminal. A
deactivated input has no power consumption, whereas if it is connected,
additional power consumption for each connected input must be considered.
That’s why we should prioritize the use of inputs that are normally deactivated
(normally open contact) and activated only for a short time. You can see the
consumption of digital inputs in the Specifications chapter.
1.11.2. INPUT PASSIVE FILTER
All inputs incorporate a passive filter implemented within the electronics. The
filter increases immunity against external noises. This filter consists of a RC
network with a cutoff frequency of 700Hz. This filter is applied to all inputs
independently of their configuration.
1.11.3. INPUT ACTIVE FILTER
When an input is edge sensitive (rising or falling edge), there is a second level
of filtration denominated active that acts according to the following criterion:
A transition in a sensitive edge digital input places the associated variable in
a non-active state and starts a timer with a value equal to Ton
2
. The period
Ton is the estimated time needed for that input to be stabilized and it will
depend on the application.
Once Ton has passed, the system verifies if the input value coincide with the
active state value, if so, the associated variable is placed in active state and
starts working a second timer with a value equal to Toff (Toff is the time that
avoids a reactivation of such an input) if the input is non-active then the
process cancels and waits for a new transaction.
During the time Ton+Toff new transactions from that input are not processed.
Once this time has passed, the system will be in conditions to attend a new
transaction in that input.
During Toff time, LOGS50 unit keeps awake counting such time situation
in which the equipment does not go to latent status increasing so the
power consumption.
2
Value assigned by the user in the Dataloggers’s configurator program. The system time resolution is 5ms approximately, if the
logger is in sleep mode, 20 ms are needed in order to proceed with the time calculation; the maximum working frequency should
not be overcome; while the time calculations are made, the logger remains in active mode without turning to sleep mode.
