User's Manual

905U-K Radio Telemetry Module User Manual
 ELPRO Technologies Pty Ltd 2001 Page 12
• Update message if the input value has not been transmitted within the update time (10
seconds - 5 days).
• After each transmission, another transmission for that input is disabled for the paralysis
time (0 – 127.5 sec).
For the 905U-K-2, the two pulse inputs may be configured to control one count value, for use
with quadrature and incremental shaft encoders. A shaft encoder is a transducer that measures
level or displacement, and has two pulse signals to indicate change of level and direction of
change.
Both pulse inputs are read at the same time.
If using an incremental encoder, the count is the value of Pulse Input 1. This pulse input value
should be used to send the true pulse count from a incremental encoder.
If using a quadrature encoder, the count is the value of Pulse Input 2. This pulse input value
should be used to send the true pulse count from a quadrature encoder.
2.3.3 Analogue Inputs
The analogue input uses a “sample time” and “warm-up time” configured by the user. The
sample time (1 minute to 20 days) “wakes” the 905U-K from sleep mode and turns on the
analogue loop supply. The “warm-up time” (0.5 – 127.5 seconds) allows the transducer to
reach rated accuracy before the 905U-K makes a measurement of the analogue signal.
For example, if the sample time is 30 minutes and the warm-up time is 10 seconds, then every
30 minutes, the 905U-K will turn on its analogue loop supply and after a further 10 seconds,
take a measurement of the analogue signal. After the measurement is taken, the 905U-K
reverts to sleep mode. If the sample time is set to zero, then the analogue loop supply will be
on continuously and measurement will be taken based on the warm-up time. If the warm-up
time is 1 second, then a measurement is taken every 1 second.
The same process occurs if an externally powered analogue signal is connected.
The measurements have a resolution of 12 bit, and an overall accuracy of better than 0.1%.
When the 905U-K 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 0.25% to 100% (0.05mA to 20mA) with a default value of
3% (0.6mA). If the change in the signal since the last transmitted value is less than the
sensitivity, then the 905U-K will not transmit the analogue value.
In addition, an update transmission of the analogue value will be transmitted if the analogue
value has not been transmitted for the update time (10 seconds - 5 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.