YOKOGAWA EJX Series, User Manual

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<5. Wiring>
29
IM 01C25A01-01E
5.2.4 Connection Example for EJX910A and EJX930A
Table 5.1 The connection example for simultaneous analog and pulse and alarm, status output. (For HART
protocol type)
Output Type Description
Analog Output
In this case, Communication
is possible (up to a distance
of 2km when a CEV cable
is used.)
Transmitter Electrical Terminal
250Ω
24V DC
+
–
Distributor
PULSE
SUPPLY
+
–
+
Pulse Output
In this case, No
communication is possible.
R
E
Transmitter Electrical Terminal
Use the Three-wire shielded cable.
Electric counter
*1
*2
Shielded Cable
PULSE
SUPPLY
+
–
+
Status Output
In this case, No
communication is possible.
Use the Three-wire shielded cable.
Shielded Cable
PULSE
SUPPLY
+
–
+
Mognetic
valve
AC power supply
External Power supply
30V DC, 120mA max
(Contact Rating)
Transmitter Electrical Terminal
E
Relay
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).
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.
*1
*2
250 Ω
R
E(10.5 to 30V DC)
Counting input
Common
24V DC
PULSE
SUPPLY
For the shielded cables in this example of
flowmeter installation, use two-wire separately
shielded cables.
This supply voltage requires a power sourse
with a maximum output current of no less than
E/R.
Distributor (or communication medium : ex. EP card)
(or communication medium : ex. EP card)
Electric counter
+
–
+
Shielded Cable
Transmitter Electrical Terminal
Example 2
In this case, Communication
is possible (up to a distance
of 200m when a CEV cable
is used) and R = 1kΩ).
*1
*2
250
Ω
R
+
–
+
PULSE
SUPPLY
Counting input
Common
For the shielded cables in this
example of flowmeter installation,
use two-wire separately shielded
cables.
This supply voltage requires a power
sourse with a maximum output current
of no less than E/R+25mA.
Recorder or
other instrument
Electric counter
E(16.4 to 30V DC)
Shielded Cable
The supply voltage requires output
impedance no more than 1/1000 of R
(load resistance).
Transmitter Electrical Terminal
Example 3
In this case, No
communication is possible
(when shielded cable is not
used).
250
Ω
R
+
–
+
PULSE
SUPPLY
Transmitter 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
E(16.4 to 30V DC)
Counting input
Common
*1
*2
The range of load
resistance R for the
pulse output.
The load resistance of pulse output should be used to 1kΩ, 2W.
If no translation of the pulse output possible by the cable length or the frequency of the pluse output, the load resistance
should be selected by calculation as shown below.
0.1
C ( µF ) × f ( kHz )
R (k
Ω
)
120
E (V)
Example of CEV cable capacitance
0.1µF/km
Where
E = Supply voltage (V)
f = Frequency of pulse output (kHz)
R = Value of load resistance (k
Ω
)
C = Cable capacitance (µF)
P = Power ratio of the load resistance
(mW)
P (mW) =
R (k
Ω
)
E
2
(V)
*1: To avoid the influence of external noise, use an electric counter which fits 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 influenced by noise comparing analog output only. Take
countermeasure for noise shown above, e.g. use shield cable etc.
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