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Chapter 9 PLC and System Maintenance. PLC System Maintenance • PLC Hardware Maintenance • Visual Inspections • Energized PLC Maintenance • Battery Maintenance • PLC Software Maintenance • Equipment and Documentation Verification • Software and Program Verification.
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Chapter 9PLC and System Maintenance PLC System Maintenance • PLC Hardware Maintenance • Visual Inspections • Energized PLC Maintenance • Battery Maintenance • PLC Software Maintenance • Equipment and Documentation Verification • Software and Program Verification
The maintenance of a PLC must be carefully documented for future reference.
PLC maintenance is performed after the application is stopped and a lockout/tagout is applied.
PLC hardware maintenance is work performed by a technician that consists of a visual inspection of a PLC, energized maintenance procedures, and battery maintenance.
A visual inspection of a PLC and PLC-related components is part of PLC hardware maintenance.
Proper personal protective equipment (PPE) must be used when performing energized maintenance on a PLC.
Backup batteries for the CPU of a PLC can be behind the hinged door or cover of the CPU or mounted on the processor card.
A PC, an interface cable, and sometimes an interface card are required to connect a PC to a PLC and use the PLC programming software.
A documented program contains address descriptions, instruction comments, rung comments, and page titles.
When connecting a PC to a PLC, the technician must be aware of certain technical issues and follow a series of steps.
PLCs have electrically erasable programmable read-only memory (EEPROM) chips to provide a backup to RAM memory.
After the machine or process is started, the PLC program must be copied to a separate medium and stored in a safe location.