YOKOGAWA EJX Series User Manual page 31

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
Analog Output
Transmitter Electrical Terminal
In this case, Communication
is possible (up to a distance
SUPPLY
of 2km when a CEV cable
is used.)
PULSE
Pulse Output
Transmitter Electrical Terminal
In this case, No
communication is possible.
SUPPLY
Status Output
Transmitter Electrical Terminal
In this case, No
communication is possible.
SUPPLY
PULSE
Simultaneous
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.
Analog
-Pulse Output
*3
Example 1
SUPPLY
In this case, Communication
is possible(up to a distance
PULSE
of 2km when a CEV cable
is used).
Transmitter Electrical Terminal
Example 2
In this case, Communication
is possible (up to a distance
of 200m when a CEV cable
SUPPLY
is used) and R = 1kΩ).
PULSE
Transmitter Electrical Terminal
Example 3
In this case, No
communication is possible
(when shielded cable is not
SUPPLY
used).
PULSE
Transmitter Electrical Terminal
The range of load
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
resistance R for the
should be selected by calculation as shown below.
pulse output.
E (V)
120
P (mW) =
*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.
+
–
+
Shielded Cable
+
–
+
PULSE
Shielded Cable
+
–
+
External Power supply
30V DC, 120mA max
(Contact Rating)
Shielded Cable
+
–
*2
+
Shielded Cable
250
+
–
+
+
–
+
0.1
R (k )
Ω
C ( µF ) × f ( kHz )
Where
2
E (V)
E = Supply voltage (V)
f = Frequency of pulse output (kHz)
R (k )
Ω
R = Value of load resistance (k
Description
Distributor
+
24V DC
– 250Ω
Use the Three-wire shielded cable.
E
*1
*2 R
Electric counter
Use the Three-wire shielded cable.
E
Relay
AC power supply
Distributor (or communication medium : ex. EP card)
For the shielded cables in this example of
24V DC
flowmeter installation, use two-wire separately
shielded cables.
250Ω
R
This supply voltage requires a power sourse
E(10.5 to 30V DC)
with a maximum output current of no less than
Counting input
E/R.
Common
*1
(or communication medium : ex. EP card)
Electric counter
For the shielded cables in this
Recorder or
example of flowmeter installation,
other instrument
use two-wire separately shielded
Ω
cables.
E(16.4 to 30V DC)
This supply voltage requires a power
*2
R
sourse with a maximum output current
Counting input
of no less than E/R+25mA.
Common
The supply voltage requires output
*1
Electric counter impedance no more than 1/1000 of R
(load resistance).
Recorder or
other instrument
250
Ω
E(16.4 to 30V DC)
*2
R
Counting input
Common
Electric counter
Example of CEV cable capacitance
0.1µF/km
C = Cable capacitance (µF)
P = Power ratio of the load resistance
)
Ω
29
<5. Wiring>
Mognetic
valve
This supply voltage requires
a power sourse with a
maximum output current of
no less than E/R+25mA.
*1
(mW)
IM 01C25A01-01E
5