Yokogawa EJX930A - Manual (Page 47)

<7. Wiring>
7-10
IM 01C25R01-01E
Table 7.2 The connection example for simultaneous analog and pulse and alarm, status output.
(For HART protocol type)
250Ω
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
+
+
Transmitter Electrical Terminal
250Ω
24V DC
PULSE
SUPPLY
+
–
Distributor
–
+
–
+
PULSE
SUPPLY
R
E
Transmitter Electrical Terminal Use the Three-wire shielded cable.
Use the Three-wire shielded cable.
Electric counter
*1
*1
*1
*1
*2
*2
*2
*2
*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
Shielded Cable
PULSE
SUPPLY
+
–
+
Mognetic
valve
AC power supply
External Power supply
30V DC, 120mA max
(Contact Rating)
Transmitter Electrical Terminal
E
250Ω
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
250Ω
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
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.
Relay
Analog Output
Pulse Output
Status Output
Simultaneous
Analog
-Pulse Output *3
Description Output Type
F0725.ai
Example 3
In this case, No communi
-cation is possible (when
shielded cable is not used).
The range of load
resistance R for
the pulse output.
Example 1
In this case, Communica
-tion is possible(up to a
distance of 2km when a
CEV cable is used).
Example 2
In this case, Communica
-tion is possible (up to a
distance of 200m when a
CEV cable is used) and R
= 1kΩ).
In this case,
Communication is
possible (up to a distance
of 2km when a CEV cable
is used.)
In this case,
No communication is
possible.
In this case,
No communication is
possible.
0.1
C ( µ F ) × f ( kHz )
≤ R (k Ω ) ≤
120
E (V)
The load resistance of pulse output should be used to 1k
Ω
, 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.
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)