505U-K Radio Telemetry Module
Page 14
© April 2002
to sleep mode. The loop voltage available for a transducer is approx. 24VDC.
If the warm-up time is set to the same or more than the sample time, then the analogue loop
will be on continuously, and the 505K will measure the signal based on the sample time. For
example, if the sample time is 10 seconds, and the warm-up time 20 seconds, then the
analogue loop will be continuously active and a measurement made every 10 secs. If the
sample time is set to zero, then a measurement is made every cycle of the 505K - that is,
0.5 sec.
Note that continuous analogue loop operation will result in a short battery life if a battery
supply is used. A solar panel and battery supply is suitable.
If an externally powered analogue signal is connected, then the same measurement process as
described above occurs .
When the 505K takes a measurement, it will transmit the analogue value if the value has
changed by more than the pre-configured sensitivity since the last transmission. The
sensitivity can be configured from 0.1% to 75% with a default value of 3%. If the change in
the signal since the last transmitted value is less than the sensitivity, then the 505K will not
transmit the analogue value.
The sensitivity value should be selected which is more than the normal analogue signal noise.
If the sensitivity is less than the signal noise, then the 505K will send a lot of un-necessary
transmissions, possibly resulting in jamming the radio channel.
An update transmission of the analogue value will be transmitted if the analogue value has
not been transmitted for during the user-configurable update period (10 seconds - 7 days). If
an update time of zero is selected, then no update messages will be sent.
If the update time expires since the last transmission, then the last measured value will be
transmitted - that is, a new measurement will not be taken. Normally the update time will be
much longer than the sample time. If the update time is less than the sample time, then
update messages may transmit the same value as the previous transmission, as a new
measurement has not yet been taken.
Overview:
•
Measurements of the analogue signal are determined by the sample time and warm-up time
•
Analogue value is transmitted if the measured value has increased by the configured
sensitivity amount since the last transmission
•
Analogue value is transmitted if the input value has not been transmitted within the update
time (10 seconds – 7 days)
•
There is no paralysis time for the analogue input.
2.4.6
Setpoint Status
The setpoint status is an internal status value, calculated by comparing the analogue input to
two configurable setpoint values. The setpoint status turns ON when the analogue input
moves below the low setpoint value, and turns OFF when it moves above the high setpoint