(1) There are three forms of programmable controller: relay output, thyristor output, and transistor output.
(2) The wiring of the output terminal is divided into independent output and common output. When the output relay or thyristor of the PLC is activated, the two output terminals of the same number are turned on. Different types and voltage levels of output voltages can be used in different groups. However, the output in the same group can only use the same type of power supply of the same voltage level.
(3) Since the output component of the PLC is encapsulated on the printed circuit board and connected to the terminal board, if the load connected to the output component is short-circuited, the printed circuit board will be burned, so the fuse should be used to protect the output component.
(4) When the relay output is used, the size of the inductive load affected the working life of the relay, so the working life of the relay is required to be long.
(5) The output load of the PLC may cause noise interference, so measures should be taken to control it. In addition, in addition to considering dangerous loads that can cause injury to the user, an external emergency shutdown circuit should be designed so that in the event of a failure of the programmable controller, the power supply of the load causing the injury can be cut off. The AC output line and the DC output line should not use the same cable, and the output line should be as far away as possible from the high-voltage line and the power line to avoid parallelism.
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Fourth, the fundamental sequence of repairing PLC.
1. Start first.
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2) If you repair an unfamiliar PLC, you should first understand its operating principle.
...
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Common types of operational faults include operator errors, terminal wiring faults, module installation faults, and power supply failures.
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