Honeywell DCP551 Mark ΙΙ User Manual page 33

Chapter 4. WIRING
HANDLING PRECAUTIONS
4-2
• Before connecting the lines, verify the model number and terminal numbers
on the label affixed to the side panel of the DCP551. After completing, always
double check to ensure all wiring has been performed correctly before turning
on the power.
• The I/O signal lines and the communications lines shall maintain at least 50
cm between them and the power supply line and power supply cables. Do not
route these cables through the same conduit or duct.
• Make sure that no crimp-style solderless wire connectors are touching an
adjacent terminal or connector.
• When connecting a thermocouple input of the DCP551 to another instrument,
make sure the instrument's input impedance totals at least 1MΩ. If less than
1MΩ, the DCP551 may not be able to detect sensor disconnection.
• Cautions when using data input devices in combination
Input of the DCP551 input or output (connected in parallel for input) to an A/D
converter, analog scanner, etc., may cause dispersion of the read data. To
prevent such occurrence, take one of the following corrective measures.
(1) Use a low-speed integral A/D converter.
(2) Insert an isolator with no switching power supply between the DCP551
and the A/D converter.
(3) Perform averaging with a personal computer when the data is read.
(4) If the device permits, insert an input filter.
• Devices and systems to be connected to this unit must have the basic insula-
tion sufficient to withstand the maximum operating voltage levels of the power
supply and input/output parts.