input module plc Wiring

 During normal smart plc operation, different methods of connecting the field device wires to the I/O Modules offer no significant advantages over each other. Field devices can be wired differently to provide safety and protection in the event of failures in field devices, or faults in their electrical circuits.
"Backups" are field devices required to operate properly to provide safety in the event of a failure of another device or fault in a circuit. If the circuit for a backup is not affected, the backup should operate properly and continue to provide safety.
 The safety of input module plc sequentially controlled systems, industrial facilities, and even personnel frequently depends on field devices (especially the backups) operating properly.
  Sink and Source connections at a DC plc analog input module are defined by whether or not the field device DC power comes from a power supply external to the PLC. Neither connection has any fault protection advantage.