ELPRO 905U - Page 30

905U Wireless I/O Module User Manual
105S Serial I/O Module
Page 30 © January 2011
Analog Change-of-state
A "change-of-state" for an analog input, battery voltage or pulse input rate is a change in value of the
signal of 3% (configurable) since the last transmission. Note that the sensitivity of 3% refers to 3% of
the analog range, not 3% of the instantaneous analog value. That is, if an analog input changes from
64% (14.24 mA) to 67% (14.72 mA), a "change-of-state" will be detected. This “change-of-state”
sensitivity is configurable between 0.8% and 75%.
Analog inputs are digitally filtered to prevent multiple transmissions on continually varying or "noisy"
signals. The input is filtered with a 1 second time constant and a 1 second debounce. The analog
outputs are filtered with a 1 second time constant. An example of an analog input and how the output
follows it is shown below:
E
0.5 sec
0.5 sec
0.5 sec
SENSITIVITY
BAND
A
B
C
D
UPDATE
TIME
INPUT
SIGNAL
OUTPUT
SIGNAL
TIME
A No transmission as the sensitivity band was not exceeded
B
The sensitivity band was exceeded, however the input returned to within the
sensitivity band before the 0.5 sec debounce time - no transmission
C Transmission occurs 0.5 sec after the sensitivity band is exceeded.
D
Another transmission 0.5 sec later as the input has changed by more than
the sensitivity band
E
The input has not changed by more than the sensitivity, however the
update time has elapsed since D.