Rosslare AC-425 - Normally Closed Input Connection; Normally Open Supervised Single EOL Resistor Input Connection; Figure 10: Normally Open Input Connection; Figure 11: Normally Closed Input Connection

Input and Output Connections
AC-425 Hardware Installation and User Manual 21
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 kΩ resistor in parallel to the input switch contacts.
A Normally Open Supervised Input has 3 states:
 Switch Open – Normal State:
Loop resistance = 8.2 kΩ
 Switch Closed – Abnormal State:
Loop resistance = 0 (short circuit)