User Manual v1.9
Manual
WI-I/O 9-K
v1.9
Page 15
50% if the level is decreasing. If an incremental shaft encoder is used, then the rate may be
scaled by scaling PRATE1. If a quadrature encoder is used, scale PRATE2. The scaling value
will determine both the 100% analog signal (e.g. 20mA) and 0% signal (e.g. 4mA). For
example, if a maximum pulse rate of 10Hz is configured, then the analog signal will be:
100% if the encoder increases at 10Hz
50% if the encoder pulse rate is 0
0% if the encoder decreases at 10Hz.
75% if the encoder increases at 5Hz
25% if the encoder decreases at 5Hz
Note that this is only true if the pulse inputs are configured for a shaft encoder. If standard pulse
inputs are used, then 0% analog signal will correspond to zero pulse rate (0Hz).
The pulse rates are treated as analog inputs and follow the rules for an analog input as described
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 WI-I/O K 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 WI-I/O K 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 WI-I/O K 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 WI-I/O K 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 WI-I/O K 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 WI-I/O K 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 WI-I/O K - 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 .
