Yokogawa digitalYEWFLO (DY) - Manual (Page 23)

<4. WIRING>
4-4
IM 01F06A00-01EN
Table 4.1 (b) The wiring example for the simultaneous analog and pulse output, the calculation formula of the
range of load registance R for the pulse output.
Connection Description
Simultaneous
Analog
-Pulse Output *3
Example 1
In this case, Communication
is possible(up to a distance
of 2km when a CEV cable is
used).
Example 2
In this case, Communication
is possible (up to a distance
of 200m when a CEV cable
is used) and R = 1k
Ω).
Example 3
In this case, No communi
-cation is possible (when
shielded cable is not used).
Ÿ
+
–
+
PULSE
SUPPLY
digitalYEWFLO Electrical Terminal
Recorder or
other instrument
This supply voltage requires
a power sourse with a
maximum output current of
no less than E/R+25mA.
Electric counter *1
E(16.4 to 30V DC)
Counting input
Common
(or communication medium)
When analog and pulse output are used, the length of communication line is subjected to wiring conditions. Refer to
example 1 to 3. If the communication carries out from amplifier, no need to consider wiring conditions.
+
–
+
For the shielded cables in this
example of flowmeter installation,
use two-wire separately shielded
cables. *4
This supply voltage requires a
power sourse with a maximum
output current of no less than
E/R+25mA.
The supply voltage requires output
impedance no more than 1/1000
of R (load resistance).
PULSE
SUPPLY
Shielded Cable
Shield
digitalYEWFLO Electrical Terminal
Outer Jacket
(or communication medium)
Ÿ
(R) *2
Counting input
Common
Recorder or
other instrument
Electric counter *1
E(16.4 to 30V DC)
(R) *2
Electric counter *1 (or communication medium)
+
–
+
250 Ÿ
(R) *2
E(10.5 to 30V DC)
Counting input
Common
24V DC
PULSE
SUPPLY
Distributor (or communication medium)
Shielded Cable
Shield
digitalYEWFLO Electrical Terminal
For the shielded cables in this
example of flowmeter installation,
use two-wire separately
shielded cables. *4
This supply voltage requires a
power sourse with a maximum
output current of no less than
E/R.
Outer Jacket
The range of load
resistance R for the
pulse output. The load resistance should be selected by calculation as shown below.
0.1
C ( μ F ) × f ( kHz )
R (k
Ÿ
)
120
E (V)
Example of CEV cable capacitance
0.1
μF/km
Where
E = Supply voltage (V)
f = Frequency of pulse output (kHz)
R = Value of load resistance (k Ÿ )
C = Cable capacitance ( μF)
P = Power ratio of the load resistance
(mW)
P (mW) =
R (k
Ÿ
)
E 2 (V)
*1: To avoid the infl uence of external noise, use an electric counter which fi ts to the pulse frequency.
*2: Resistor is not necessary in case of an electric counter which can receive contact pulse signal directly.
*3: When using analog and pulse output simultaneously, the HART communication may be infl uenced by noise comparing analog output
only.
*4: Signal Cable for ADMAG AXF, AXFC-0 (No Termination) is available.