Input and Output Connections
AC-425 Hardware Installation and User Manual
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Figure 10: Normally Open Input Connection
4.1.2
Normally Closed Input Connection
A Normally Closed Input has two states:
Switch Closed – Normal State:
Loop resistance = 0 (short circuit)
Switch Open – Abnormal State:
Loop resistance = Infinite (open circuit)
Figure 11: Normally Closed Input Connection
4.1.3
Normally Open Supervised Single EOL Resistor Input
Connection
Connect an 8.2 k
Ω
resistor in parallel to the input switch contacts.
A Normally Open Supervised Input has 3 states:
Switch Open – Normal State:
Loop resistance = 8.2 k
Ω
Switch Closed – Abnormal State:
Loop resistance = 0 (short circuit)
