Omron H7EC Manual page 97

Precautions
!Caution
Do not use the product in locations subject to flammable or explo-
sive gases. Doing so may result in explosion.
The service life of the output relays depends on the switching
capacity and switching conditions. Consider the actual application
conditions and use the product within the rated load and electrical
service life. Using the product beyond its service life may result in
contact deposition or burning.
Do not disassemble, repair, or modify the product. Doing so may
result in electric shock, fire, or malfunction.
Do not allow metal objects or conductive wires to enter the product.
Doing so may result in electric shock, fire, or malfunction.
I External Power Supply
The capacity of the external power supply is 100 mA at 12 V. When
using a 24 VAC/12 to 24 VDC power supply, reduce the load with the
power supply voltage, as shown in the following diagram (DC power
supplies only).
(DC v ltage ppl only)
100
20
10.8
I Power Supplies
When turning the power ON and OFF, input signal reception is possi-
ble, unstable, or impossible as shown in the diagram below.
Power
ON
supply
OFF
200 ms 0 to 90 ms
Input Impossible
Unstable
Turn the power ON and OFF using a relay with a rated capacity of 10
A minimum to prevent contact deterioration due to inrush current
caused by turning the power ON and OFF.
Apply the power supply voltage through a relay or switch in such a
way that the voltage reaches a fixed value immediately, otherwise
they may not be reset or a counter error may result.
Be sure that the capacity of the power supply is large enough, other-
wise the counter may not start due to inrush current (reference value:
approx. 10 A, 1.2 ms at 26.4 VAC) that may flow for an instant when
the counter is turned ON.
Make sure that the fluctuation of the supply voltage is within the per-
missible range.
Make sure that the voltage applied is within the specified range, oth-
erwise the internal elements of the counter may be damaged.
15
Power pply vol age C)
5 ms 0 to 1 s
Possible Impossible
Unstable
I Transistor Output
The transistor output of the H7CX is isolated from the internal cir-
cuitry by a photocoupler, so the transistor output can be used as both
NPN and PNP output.
NPN output
Load
+
Power for load
The diode connected to the collector of the output transistor is used
to absorb inverted voltage that is generated when an inductive load is
connected to the H7CX.
Counter
+
Power for load
I Changing the Set Values
When changing the set value during operation, because the H7CX
uses a constant read-in system, output will turn ON if the set value is
equal to the present value.
I Operation with a Set Value and
Present Value of 0
If the set value and present value are both 0, output will turn ON.
Output will turn OFF during reset.
I Using the Prescaling Function
Observe the following points when setting a prescale value.
• Set the set value to a value less than {Maximum countable value −
Prescale value}.
Example: If the prescale value is 1.25 and the counting range is
0.000 to 999.999, set the set value to a value less than
998.749 (= 999.999 − 1.25).
• If the set value is set to a value greater than this, output will not turn
ON.
Note: Output will turn ON, however, if a present value overflow occurs
(FFFFFF or FFFF).
• Setting the prescale value incorrectly may result in incorrect count-
ing operation. Be sure to set the prescale value correctly.
I DIP Switch Setting
Ensure that the power is turned OFF before changing DIP switch set-
tings. Changing DIP switch settings with the power turned ON may
result in electric shock due to contact with terminals subject to high
voltages.
I Power Failure Backup
All data is stored in the EEPROM when there is power failure. The
EEPROM can be overwritten more than 100,000 times. EEPROM is
overwritten when the power is turned OFF or when settings are
changed.
Multifunction Preset Counter
PNP output
Load
+
Power for load
Inductive load
H7CX
C-103