Rockwell Automation 1755-OF8 GuardPLC Controller Systems - Manual (Page 62)

62 Publication 1753-UM001C-EN-P - March 2010
Chapter 5 Wire the GuardPLC 2000 Controller and I/O
Safety-related Digital
Outputs The status of digital outputs is indicated via status indicators when the
controller or module is in Run mode.
GuardPLC 2000 controller outputs are rated at 2 A per point, but the
total load of all 16 outputs on a single module must not exceed 8 A.
If an overload occurs, the affected outputs are turned off. When the
overload is eliminated, the outputs are under the control of the
controller and are energized based on the user program code.
An output is in the safe state when it is de-energized. Therefore,
outputs are switched off when a fault that affects the safe control of
those outputs occurs.
For connection of a load, the reference pole L- of the corresponding
channel group must be used. Although L- poles are connected
internally to L- on the power supply input, it is strictly recommended
to connect the L- reference poles only to their corresponding output
group. EMC testing was performed in this manner.
Safety-Related Analog
Inputs (1755-IF8) GuardPLC analog inputs provide for the unipolar measurement of
voltages from 0…10V, referenced to L-. A 10 k
Ω
shunt is used for
single-ended voltage signals. With a 500
Ω
shunt resistor, currents
from 0…20 mA can also be measured.
The feeder lines should be no more than 300 m (984 ft.) in length. Use
shielded, twisted-pair cables, with the shields connected at one end,
for each measurement input. See the instructions for connecting
shielded cabling to the shield contact plate on page
48 .
TIP
Inductive loads can be connected without a protection diode on
the load, because there is a protection diode located within the
GuardPLC device. However, Rockwell Automation strongly
recommends that a protection diode be fitted directly to the
load to suppress any interference voltage. A 1N4004 diode is
recommended.