6
PREPARATORY PROCEDURES AND SETTING
6.2 Fail-Safe Circuit
6 - 5
1
OVERVIEW
2
SYSTEM
CONFIGURATION
3
SPECIFICATIONS
4
FUNCTIONS
5
ACCESS VIA NETWORK
MODULES
6
PREPARATORY
PROCEDURES AND
SETTING
7
I/O NUMBER
ASSIGNMENT
8
MEMORIES AND FILES
When the C Controller system is powered on/off, some control output may not be normal
for a moment because of a delay or a rise time difference between the C Controller system
power supply and the external power supply (especially DC) for the control target.
In the case of a DC output module, for example, when power is applied to the control
target first and then to the C Controller system, the DC output module may temporarily
generate incorrect output at power-on of the C Controller system.
Therefore, it is necessary to configure a circuit by which power is applied to the C
Controller system first.
Also, if the external power supply or C Controller module is faulty, an abnormal operation
may occur.
To prevent such abnormal operation from resulting in failure of the entire system, configure
fail-safe circuits external to the C Controller module for the areas where an abnormal
operation will lead to mechanical damage and/or accidents (emergency stop circuit,
protection circuit, interlock circuit, etc.)
A circuit example for system design is provided on the next page.
WARNING
For the following controls, configure an interlock circuit in the user
program to ensure that the entire system will always operate safely.
(1) Changing data of a running C Controller module from the
development environment (personal computer) connected
(2) Changing the operating status
(3) Operation from the development environment (personal
computer)
Especially, in the case of control from an external device to a remote
C Controller module, immediate action cannot be taken for a
problem on the C Controller module due to a communication failure.
To prevent this, configure an interlock circuit in the user program and
determine corrective actions to be taken between the external
device and C Controller module in case of a communication failure.
CAUTION
Do not install the control lines or communication cables together
with the main circuit lines or power cables.
Keep a distance of 100mm (3.94 inches) or more between them.
Failure to do so may result in malfunction due to noise.
When a device such as a lamp, heater, or solenoid valve is
controlled through an output module, a large current (approximately
ten times greater than normal) may flow when the output is turned
from off to on. Take measures such as replacing the module with
one having a sufficient current rating.
When the C Controller module is powered off to on or reset, the time
for the C Controller to reach the RUN status varies depending on the
system configuration, parameter setting or program capacity.
Design the system so that the whole system operates at the safe
side even when the time required for the C Controller module to
reach the RUN status varies.
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