Gai-tronics 378-002 Monitored Input Module (MIM) Station Manual de usuario descargar pdf (Pagina 6)

Pub. 42004-490A

Model 378-002 Monitored Input Module Station Page 6 of 10

f:\standard ioms - current release\42004 instr. manuals\42004-490a.doc

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Model 2: IDC Single Normally-Open (N.O.) Switch

In this configuration, only one normally-open dry contact closure may be installed per supervised line. In

this mode, the loop is monitored for open circuits, wire-to-wire short circuits (across + and −), and ground

faults. When the contact closure is not active (open), the loop appears as 20.1 k load (15 k in series

with 5.1 k). This appears on the input to the MIM and indicates a healthy loop. When the contact

closure is active (closed), the 15 k resistor is bypassed.

Figure 3. IDC Single Normally-Open Switch

The circuit then sees only the 5.1 k load. This changes the value of the input and indicates to the MIM

that the contact closure is active. If there is a short across + and −, if either leg is grounded, or if a break

occurs on either leg, the MIM indicates that a fault has occurred.

OTE: The terminating resistors are not included with the MIM. These resistors are included in a kit

(12509-003) that must be ordered separately.

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Gai-tronics 378-002 Monitored Input Module (MIM) Station Manual de usuario Pagina 6