National Instruments FP-RLY-420 - Manual (Page 9)

© National Instruments Corp. 9 FP-RLY-420
After the module has been inserted into a terminal base (and
power is applied), the green POWER indicator lights and the
FP-RLY-420 informs the network module of its presence. When
the network module recognizes the FP-RLY-420, the network
module sends initial configuration information to the FP-RLY-420.
After receiving this initial information, the green READY
indicator lights and the FP-RLY-420 is in its normal operating
mode. In addition to the green POWER and READY indicators,
each channel has a numbered, green, output state indicator that
lights when the channel is in the ON state.
Isolation and Safety Guidelines
Caution Read the following information before
attempting to connect ANY circuits that may contain
hazardous voltages to the FP-RLY-420.
This section describes the isolation of the FP-RLY-420 and its
compliance with international safety standards. The outputs are
isolated from the backplane of the terminal base with an isolation
barrier designed and tested to protect against fault voltages of up to
3000 Vrms. In addition, the FP-RLY-420 provides double
insulation (compliant to UL and IEC safety standards) for working
common-mode voltages of 250 Vrms. Safety standards (such as
those published by UL and IEC) require the use of double
insulation between hazardous voltages and any human-accessible
parts or circuits. You should never attempt to use any isolation
product between human-accessible parts (such as DIN rails or
monitoring stations) and circuits that may be at hazardous
potentials under normal conditions, unless the product is
specifically designed (as the FP-RLY-420 is) for such an
application.
Even when a product like the FP-RLY-420 is used in applications
with hazardous potentials, follow these guidelines to ensure a safe
total system:
• The safety isolation of the FP-RLY-420 is from input to output,
not between channels on the same module. If any of the
channels on a module are wired at a hazardous potential,
ensure that all other devices or circuits connected to that
module are properly insulated from human contact.