User manual

User Manual
man_905K_1.10.doc Page 15
below.
2.4.5 Analog Inputs
The analog input can measure from 0 – 24mA or 0 – 10VDC. Current or voltage input can be
selected by an internal selector (refer Installation section of this manual). The mA input can be
used for conventional 4-20mA signals or 0-10mA or 0-20mA. The voltage input can be used for
0-5 or 0-10VDC signals. The 905K unit is factory configured for a 4-20mA signal, however the
user can calibrate the unit for other ranges. The measurement resolution is 12 bit.
The analog input uses a “sample time” and “warm-up time” configured by the user. The sample
time (0 – 32727 sec or 9.1hours) “wakes” the 905K from sleep mode and turns on the analog
loop supply. The “warm-up time” (0 – 100 seconds) allows the transducer to reach rated
accuracy before the 905K makes a measurement of the analog signal.
For example, if the sample time is 30 minutes and the warm-up time is 10 seconds, then every 30
minutes, the 905K will turn on its analog loop supply and after a further 10 seconds, take a
measurement of the analog signal. After the measurement is taken, the 905K reverts 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 analog loop will be
on continuously, and the 905K 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 analog loop will be
continuously active and a measurement made every 10 secs. If the sample time os set to zero,
then a measurement is made every cycle of the 905K - that is, 0.5 sec.
Note that continuous analog 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 analog signal is connected, then the same measurement process as
described above occurs .