Rockwell Automation 1755-OF8 GuardPLC Controller Systems - Manual (Page 69)

69 Publication 1753-UM001C-EN-P - March 2010 69
Chapter
6
Wire 1753-IB16, 1753-OB16, and
1753-IB20XOB8 Modules
Introduction
Safety-related Digital
Inputs The status of digital inputs is indicated via status indicators when the
module is in Run mode.
Follow the closed-circuit principle for external wiring when
connecting sensors. To create a safe state in the event of a fault, the
input signals revert to the de-energized state (0). The external line is
not monitored, but a wire break is interpreted as a safe (0) signal.
The GuardPLC 1600 and GuardPLC 1800 controllers provide power to
input devices through their LS+ terminals. However, input devices
with their own dedicated power supply can also be connected instead
of contacts. The reference pole (L-) of the power supply must then be
connected to the reference pole (L-) of the appropriate GuardPLC
input group. See the wiring diagrams in
Appendix C for examples.
In general, the LS+ terminals, not L+ on the power supply connection,
should be used to supply voltage for safety inputs. Each LS+ features
individual short-circuit and EMC protection. Due to current limitations,
use LS+ for only the safety inputs on the same terminal plug.
An EN 61000-4.5 surge impulse can be read as a short-duration HI
signal in some modules. To avoid an error, either:
•
install shielded input lines to prevent effects of surges in the
system.
•
implement software filtering in the user program. A signal must
be present for at least two cycles before it is evaluated.
Topic Page
Safety-related Digital Inputs 69
Safety-related Digital Outputs 70
Power Supply Connections 70
Wire the 1753-IB16 Input Module 71
Wire the 1753-OB16 Output Module 73
Wire the 1753-IB20XOB8 Combination Module 75