Page 494 - Sensors and Control Systems in Manufacturing
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Communications
FIGURE 9.7 Relationships between sensor, processor, and actuator activities in the 447
PLC.
The modules are designed to meet the following requirements on
the input side:
• Protection against loss of the signal as a result of overvoltage
or incorrect voltage
• Elimination of momentary interface impulses
• Possibility of connecting passive sensors (switches, push
buttons) and initiators
• Recognition of error status
It depends on the manufacturer whether all requirements are met
or only some of them. Figure 9.8 shows the basic elements of an input
module.
FIGURE 9.8 Elements of an input module.
