Rockwell Automation T3418F ICS Regent Monitored Digital Input Modules, Field Powered (Type F) - Manual (Page 16)

Monitored Digital Input Modules, Type F (T3411F, T3418F)
1 6
Industrial Control Services
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
input.
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
The actual voltage levels for the T3418F are half that shown
in Table 1, e.g. the On/Off threshold is 6 Vdc and a line
monitored Switch Open is 8 Vdc. However, when configuring
the input module voltage thresholds, the settings should be as
shown in Table 1, i.e. 4 Vdc, 12 Vdc and 20 Vdc. The input
module will automatically halve these setting values for the
input module reference voltages.
Keying
The I/O chassis can be physically keyed to prevent accidental
damage caused by inserting a module into a slot wired for a
different module type. Figure 10 illustrates how the slot keys
are installed on the I/O chassis slot field wiring connectors.
The slot key positions for the monitored digital input module
are listed in Table 2.
Note: