User Manual v1.9
Manual
WI-I/O 9-K
v1.9
Page 37
message during the paralysis time - this is to prevent overcrowding of the radio channel. An
example could be a system monitoring environmental alarms. Normally there would be few
change messages, but under abnormal conditions, a lot of change messages could be generated in
a short time period. The paralysis time will allow each module to send the first change message,
but subsequent change messages are disabled during the paralysis time.
There is a separate paralysis time for digital change messages and pulse change messages. There
is no paralysis time for analog inputs.
4.4
Analog Input
There are three parameters which
may be adjusted for the analog
input.
The
change sensitivity
is the
amount of change since the last
transmission which will trigger
another transmission for this
input. For example, if the last
transmitted value of the input
was 55.0%, and the sensitivity is
1.2%, then another transmission
will occur if the measured input value is less than 53.8% or more than 56.2%. If change messages
are not required, then a sensitivity of 75% should be selected.
The WI-I/O K does not have any filtering on the analog measurement. If the analog signal is
noisy, then a lot of change messages can be generated if the sensitivity value is set too low. The
sensitivity should be set to be greater than the signal noise. For example, if there is a signal
oscillation of 1% on the input, then a sensitivity of less than 1% will result in continuous change
transmissions which could overload the radio channel.
The
sample time
is the time period for each analog input measurement. Between measurements,
the WI-I/O K will operate in "sleep" mode. When the sample time has expired, the WI-I/O K
will turn on the analog loop power supply. After a further time, called the
warmup time
, the
WI-I/O K will make a measurement of the input. The warmup time allows the transducer to
stabilise and become accurate after the loop supply is turned on.
The sample time may be entered in seconds, between 0 and 32 767 seconds. The warm-up time
may be entered in seconds between 0 and 127 seconds.
If the sample time is less than or equal to the warm-up time, then the analog loop supply will be
always on and measurements of the analog signal will be taken based on the sample time. If the
sample time is zero, then a measurement will be taken every 0.5 sec.
The analog loop supply will be always on, so this situation is not suitable for a battery power
