Rockwell Automation 1734-IB4D POINT I/O 24V dc 4-Channel Discrete Input Module Installation Instructions - Manual (Page 8)

8 POINT I/O 24V dc Digital Diagnostics Input Module
Publication 1734-IN029A-EN-E - January 2007
Before You Begin
The module supports remove and insert under power, auto-address,
and auto-baud in compliance with the POINTBus backplane. Each
input is a sinking dc input with short-circuit and open-wire detection.
The sensor source voltage is derived from the user auxiliary power
and used as I/O power.
Understand Short-circuit Detection
The sensor source voltage (SSV) for each input is protected against
short circuits. For currents above 200 mA, a fault signal is issued and
the input LED indicator is illuminated solid red. A thermally-actuated
smart-power device or PTC is used as the protection means. On a
per-input basis, the circuit and produced data automatically reset and
SSV energizes upon removal of the short circuit. An individual fault
signal is issued for each shorted SSV condition.
The shorted input LED indicator illuminates red to denote
short-circuit fault status.
See the section on interpreting LED indicators for related information.
When the SSV is loaded to the maximum rated current of 50 mA, a
voltage drop of as much as 2.5V dc can exist between the user
auxiliary power and the SSV connection. For example, for a supply of
10V dc to a sensor with power derived from the SSV, a supply of
12.5V dc is needed at the auxiliary power connection.