Connecting The Field Wiring - Automation Direct DL405 User Manual

11–4
D4-02DA 2-Channel Analog Output

Connecting the Field Wiring

Wiring Guidelines
User Power
Supply
Requirements
Load
Requirements
Using the
1–5 VDC Range
Your company may have guidelines for wiring and cable installation. If so, you should
check those before you begin the installation. Here are some general things to
consider.
S
Use the shortest wiring route whenever possible.
S
Use shielded wiring and ground the shield at the module or the power
supply return (0V). Do not ground the shield at both the module and the
transducer.
S
Do not run the signal wiring next to large motors, high current switches,
or transformers. This may cause noise problems.
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Route the wiring through an approved cable housing to minimize the risk
of accidental damage. Check local and national codes to choose the
correct method for your application.
The D4–02DA requires a separate power supply. The DL430/440/450 CPUs,
D4–RS Remote I/O Controller, and D4–EX Expansion Units have built-in 24 VDC
power supplies that provide up to 400mA of current. If you only have one analog
module, you can use this power source instead of a separate supply. If you have
more than one analog module, or you would rather use a separate supply, choose
one that meets the following requirements: 24 VDC $10%, Class 2, 300mA (per
module).
Each channel can be wired independently for voltage or current.
S
Current loads must have an impedance between 5 and 500 ohms.
S
Voltage loads must have an impedance greater than 2K ohms.
Since the module provides a 0–10V signal on the voltage outputs, you have to use
the current outputs and a precision resistor to generate the 1–5V signal.
With a 250 ohm precision resistor across the current outputs, the module converts
the current signals to voltage for you (4mA x 250 ohms = 1V, 20mA x 250 ohms = 5V).
The transducer should be connected in parallel with the precision resistor and the
parallel equivalent resistance should be approximately 250 ohms ($0.1%). Field
devices that have impedances of greater than 250K ohms can be used with less than
0.1% additional inaccuracy. See the following diagram.
Module (internal equivalent circuit)
R R
p
L + 250W
) R
R
p
L
R = value of external precision resistor
p
R = load impedance
L
Only one channel shown
Precision Load resistance
resistor (DC input impedance)
+I
+
R R
1–5V
p L
–I
–
+V
Not Used
–V
0V