4-2
Chapter 4. WIRING
Handling Precautions
• Before wiring the DCP31, check the controller catalog No. and
terminal Nos. on the label on the rear of the body. After wiring
the DCP31, be sure to check the wiring for any mistakes.
• Maintain a distance of at least 50 cm between I/O leads or com-
munications leads and the power lead. Also, do not pass these
leads through the same piping or wiring duct.
• When wiring with crimped terminals, take care to prevent con-
tact with adjacent terminals.
• When connecting the DCP31’s thermocouples in parallel to other
controllers, make sure that the total input impedance of the
other controller is at least 1MΩ.
If the input impedance is less than 1MΩ, the DCP31 may not be
able to detect sensor disconnection.
• When inputting the DCP31’s I/O (parallel connection in case of
input) to an A/D converter or analog scanner, read data may
fluctuate.
To prevent this, adopt one of the following measures.
(1) Use a low-speed, integrating type A/D converter.
(2) Insert an isolator without a switching power supply between
the DCP31 and A/D converter.
(3) Average data on a personal computer when reading data.
(4) If possible, set a filter for the input.
• Provide the wiring for the instrument power supply with a mains
power shutoff switch within reach of the instrument operator.
• Provide a delay-type (T) rated current 1A and rated voltage 250 V
fuse on the instrumentation power supply wiring. Connect to live
conductor. (IEC 127)
• Devices and systems to be connected to this unit must have
reinforced insulation or double insulation sufficient to withstand
the maximum operating voltage levels of the power supply and
input/output parts.
• Do not connect 3 crimp terminals or more to the same terminal
screw.
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