Rockwell Automation 1732DS-IB8 User Manual page 25

The test output terminal is also used as a power supply to source an
external input device to the safety input terminal.
Example Use of a 1791DS-IB12 Module
Safety
Input
Terminal
24V
When the external input contact turns on, a test pulse is output from
the test output terminal to diagnose the field wiring and input
circuitry. Using this function, short-circuits between input signal lines
and the power supply (positive side), and short-circuits between input
signal lines can be detected.
Short-circuit Between Input Signal Lines
V
24V
G
T0
IN0
T1
IN1
Understand the Operation of Safety Functions
24V dc Output with Test Pulse
External Contact
24V
0V
External Contact
Short-circuit Between Input Signal Lines and
Power Supply (Positive Side)
External Contact
External Contact
Short-circuit Between Input Signal Lines
Publication 1791DS-UM001H-EN-P - April 2009
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