Rockwell Automation T7411 ICS Regent+Plus Monitored Digital Input Modules 24VDC - Manual (Page 12)

Monitored Digital Input Modules (T7411)
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Industrial Control Services
Figure 7. Line Monitoring, Single Switch Connected to
Redundant Modules.
With the line monitor device installed, the input voltage, Vin,
has four possible states as represented in Table 1. When the
input module reads the input, the reference voltage, Vref, is
set to the values shown in Table 1 to detect the state of the
field input and wiring.
Table 1. Input States and Reference Voltage Thresholds.
Vref
Threshold
Voltage Vin with Line
Monitor
Vin without
Line Monitor
Stuck-on Test 32 Vdc
24 Vdc Wire Open Switch Open
Open Circuit 20 Vdc
16 Vdc Switch Open NA
On/Off 12 Vdc
8 Vdc Switch Closed NA
Short Circuit 4 Vdc
0 Vdc Wire Short Switch Closed
Stuck-Off Test -5 Vdc