Omron CP1H-X40D Operation Manual page 472

Analog I/O Units
Note
438
(1) Connect the shield to the FG terminal to prevent noise.
(2) When an input is not being used, short the + and − terminals.
(3) Separate wiring from power lines (AC power supply lines, high-voltage
lines, etc.)
(4) When there is noise in the power supply line, install a noise filter on the
input section and the power supply terminals.
(5) Refer to the following diagram regarding wiring disconnections when volt-
age input is being used.
A
Analog
output
device
B C
1
Analog
output
device
2
24 VDC
For example, if analog input device 2 is outputting 5 V and the same
power supply is being used as shown above, about 1/3, or 1.6 V, will be
applied at the input for input device 1.
Consider the following information on open input circuits when using volt-
age inputs. Either use separate power supplies, or install an isolator at
each input.
If the same power supply is used as shown in the following diagram and
an open circuit occurs at point A or B, an unwanted current flow will occur
as shown by the dotted lines in the diagram, creating a voltage at the
other input of about 1/3 to 1/2. If the 1 to 5 V range is being used, the
open-circuit detection function will not operate. Also, if there is an open
circuit at C, the open-circuit detection function will not operate because
the negative sides are the same.
(6) When external power is supplied (when range codes are set), or when the
power is interrupted, there may be a pulse status analog output of up to
1 ms. If this status is a problem, take the following measures.
• Turn ON the power to the CP1H CPU Unit, check the operation status,
and then turn ON the power at the load.
• Turn OFF the power to the load and then turn OFF the power to the
CP1H CPU Unit.
Section 7-4