Rosslare AC-225? AC-225IP? AC-225U - Page 20

Input and Output Requirements
Normally Open Supervised Single Resistor Input Connection
Connect an 8.2K resistor in parallel to the input switch
contacts.
Normally Open Supervised Input has 3 states:
• Switch Open - Normal State:
Loop resistance = 8.2K.
• Switch Closed – Abnormal State:
Loop resistance = 0 (short circuit).
• Open circuit across input terminals - Trouble State:
Loop resistance = Infinite (open circuit).
Figure 10: Normally Open Supervised Input (Single Resistor)
AC-225 Hardware Installation and User Guide Page 19