Cisco Physical Access Gateway Manuel d'utilisateur télécharger pdf (Page 55)

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What is a supervised input?

 An unsupervised input has 2 states, active or inactive.

 Supervised input has 4 states, active, inactive, short, and open.

 Why do I care? What if a wire is cut or shorted between the module input

and a normally open device. The server could not determine this and the

device would remain in inactive state even when the switch is closed!

 How do I make the device/input supervised?



Use 2 1K resistors in the circuit. In the inactive state, the circuit measures

2000 ohms, in the active state, the circuit measures 1000 ohms, short state

would measure 0 ohms, and open state would measure infinite ohms. Now I

can tell if a wire is cut or shorted

OHMs State Door

State

Error

Posted?

Input

Trusted?

2000 Inactive Closed No Yes

1000 Active Open No Yes

Zero Short ????? Yes No

Infinite Open ????? Yes No

Example used: Door Sensor

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Cisco Physical Access Gateway Manuel d'utilisateur Page 55