Smart Type
B-526-10N-E
23
8.5 Preamp-to-Receiving Instrument Hookup with Smart Type ULTRA register
The 2-wire signal transmission system used in this flowmeter furnishes DC power to the meter. It serves as the
power line and signal line as well with pulse or analog current output.
An OVAL receiving instrument can be coupled directly, but instruments in general which are designed to accept
a voltage signal input require a load resistor RL connected in series for voltage conversion. Since the voltage
signal level varies with the load resistance value, determine the load resistance value by referring to the
receiving instrument specifications and the acceptable load resistance range shown below.
Communications with a PC (Smart Communication Unit) requires a 250 to 1000
Ω
load.
●
In case a voltage input is fed to the receiving instrument
DC POWER
R
L
+
−
VOLT. SIGNAL
TO RECEIVING
INSTRUMENT
+
−
OPEN COLLECTOR OUTPUT
30V, 50mA max.
FLOWMETER
REGISTER
GND
+
−
2
1
4
3
+
−
(SMART COMUNICATION UNIT)
PC
(SMART COMUNICATION UNIT)
PC
Output
Voltage Signal (V)
Pulse Output
ON
/
OFF
=
(20mA
×
R
L
)
/
(4mA
×
R
L
)
Analog
Output
(4mA
×
R
L
)
-
(20mA
×
R
L
)
at 0
~
FS
NOTE: With the relationship with
supply voltage E, select
the load resistance value
RL such that the current
flowing into the transistor
is held below 50mA.
Fig. 8.1
Supply Voltage (VDC)
R
L
, (Load Resist)
0
12V 17.25V
45V
1000Ω
1571Ω
250Ω
33V
Area: Operating range
Area: Acceptable Communication range
R
L
=
E
−
12V
21mA
EXAMPLE: If supply voltage is 24V dc with load
resistance 250Ω, then a 1 to 5V dc
output is obtained.
Acceptable Load Resistance Range
Fig. 8.2
Summary of Contents for ULTRA UF-II
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