Westermo RM-505U-K - Manual (Page 33)

man_505U-K_1.4.doc Dec 2008
    ELPRO Technologies Pty Ltd 2008 Page 33
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 analogue inputs.
4.4 Analogue Input
There are three
parameters which may
be adjusted for the
analogue 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 505K does not have any filtering on the analogue measurement. If the analogue 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 analogue input measurement. Between
measurements, the 505K will operate in "sleep" mode. When the sample time has expired,
the 505K will turn on the analogue loop power supply. After a further time, called the
warmup time, the 505K 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 100 seconds.
If the sample time is less than or equal to the warm-up time, then the analogue loop supply
will be always on and measurements of the analogue 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 analogue loop supply will be always on, so this situation is not suitable for a battery
power supply.