Total Solution for Industrial Automation
Design Precautions (
Warning)
Please install a safety circuit to protect entire control system in case of an
unexpected power shut-down and PLC module malfunction. Such anomalies may
severely compromise the integrity of the overall system.
External to the PLC, please install circuits and switches to safeguard the system from
mechanical damages (ex. Emergency stop, upper/lower limit switches,
forward/reverse direction interlocking circuits, etc)
When the PLC detects either of the following failure conditions, it may stop
operation and turn off all outputs.
-
The overcurrent protection or overvoltage protection of the power supply
module is activated.
-
The PLC CPU detected a failure, such as the watchdog timer error or module
installation failure, with its self-diagnostic function.
In addition, all outputs may be turned on when there is a failure that the PLC CPU
cannot detect, such as in the relay or TR terminal. Build an extra monitoring circuit
that will monitor any output signal that could cause serious accidents.
A greater than normal current passed through the PLC for an extended period of
time, or a short-circuited load flows in the output module may cause a fire.
Build a circuit that turns on the external power supply after the PLC power supply is
turned on. If the external power supply is turned on first, it could result in output
failure or malfunction.
In order to ensure that the system operates safely, please configure an interlock
circuit in the scan program for the following situations.
-
When exchanging data with computer or other devices.
-
When operated by a computer or other devices.
Not doing so could result in output failure or malfunction.
Precautions for design (
Caution)
Do not bundle the input/output signal or communications cables with the main
circuit and power cables. They should be installed at least more than 100 mm
(3.94inches) apart. Not doing so could result in output failure or malfunction.