User`s manual
Within the two pre-programmed distances the output signal of the UT-21-4
and the UT-22-4 transmitters are proportional to the distance in
accordance with Figures 7 and 8.
X
A
X
B
20 mA
4 mA
X
A
> X
B
X
A
X
B
20 mA
4 mA
X
A
< X
B
20.5 mA
3.8 mA
3.8 mA
20.5 mA
I
out
I
out
distancedistance
Figure 7
Transfer characteristic of units with current output
X
A
X
B
10 V
X
A
> X
B
X
A
X
B
10 V
X
A
< X
B
10,5 V
< 20 mV
10,5 V
< 20 mV
UT >13V
U
out
U
out
distancedistance
Figure 8
Transfer characteristic of units with voltage output
After the first power up the unit will work with the factory settings and
afterwards the characteristic configuration is as can be seen below:
SWITCHES: X
A
= X
max
/2, X
B
= X
A
+ 0.1 m
TRANSMITTERS: X
A
= X
min
, X
B
= X
max
Distance parameters X
A
, and X
B
can be changed by programming by placing a
good reflecting target at the distance to be programmed and by selecting the
relevant menu. The unit will measure and store (learn) the distance.
MICROSONAR receives the echo coming from the nearest reflecting surface
within the range. The range of the unit with Factory Setting is between X
min
and
X
max
. (Nominal range)
If the target is moving within smaller range it is advisable to reduce the range
by far-end blocking which should be done by programming the limit of X
T.
Factory default X
T
= X
max
Targets
present
Measured
distance
1,2,3 X
1
2,3 X
2
3 Error
Sensor surface
Xmin
Xmax
A
X
X
X
2
B
T
X
1
1
2
3
0
Figure 9
Far-end blocking will prevent evaluation of echoes beyond X
T
. Should the echo
be lost for any reason (unstable echo, intensive movement of air), the object
behind X
T
will not be taken into consideration but an error will indicate the lack
of a valid echo.
Error indication at the output of different units:
SWITCH STATUS: off (open)
TRANSMITTER I
OUT
= 3.6 mA
TRANSMITTER U
OUT
= 0 V
The signal processing of the unit can be adapted to the most diverse
requirements and conditions of an application. The two programmable
parameters influencing signal processing are the averaging number and the
number of discarded echoes.
Averaging number: a (1, 4, 8, 16)
To reduce random measurement errors the unit will not provide output on the
basis of a single measurement but by taking the average of the last a number
of distance samples.
Increasing the averaging number reduces the small fluctuation of the output
signal caused by the uncertain movement of the target or by measurement
error (caused by noise). On the other hand this will cause a speed-dependent
target tracking error which diappears after a a⋅T
p
settling time or switching
delay
Number of discarded echoes: k (1, 3, 5, 10)
Under disadvantageous conditions (air movement, not perpendicular or bad
reflecting surfaces) some of the echoes may miss the sensor. Paying
immediate attention to this, might lead to frequent error indication and big
measurement errors. Therefore the unit first checks the measured distance to
verify that it is within range.
Measured distances outside the range will be disregarded during average
calculation and the output signal maintains the former value. The unit can
disregard k number of consecutive distance samples before an error will be
indicated.
If due to bad reflection a substantial number of echoes are lost and the number
of invalid (incorrect) echoes between two valid ones, is smaller than k the unit
will maintain the output signal continuously. The greater the programmed value
of k, the less sensitive the unit will be to invalid echoes but the reaction time for
error indication will increase. To maintain continuous operation the
programmed range should be kept as narrow as possible (with far-end
blocking).
The greater the speed of the target the smaller the chosen averaging number
should be. The worse the reflection of the target the higher the chosen value of
k (number of discarded echoes) should be.
5.2 PROGRAMMING
1. Touch-Magnet Programming
The magnetic screwdriver (with its cap removed) should be used to touch the
points on the enclosure marked A or B according to Figure 10. These steps
will hence be indicated as A or B.
Touch-Magnet Programming is only possible if it is not disabled and the PRG
wire is free. Disabling can be programmed by both Touch-Magnet
Programming or by cable contacting, but it can only be undone by cable
contacting.
Figure 10
Position of the magnetic screwdriver during programming
2. Programming via cable contact
The steps A or B can be realized by connecting the PRG wire to +U
S
or GND
respectively.
This can be done by using either the switch or two push buttons connected
for the period of the programming, or by simply connecting the ends of the
cables.
Different states in the programming procedure are indicated by the three LEDs.
Steps A and B (magnet touch, wire connection) should be maintained till the
effect will be indicated by the relevant change of the LED status.
Red
LED
Yellow
LED
Green
LED
Red Yellow
Green
off
on
blinking
Figure 11
Arrangement of the LEDs and LED state interpretation in the manual