User's Manual

Table Of Contents
3.7 Digital I/O Wiring
Both the Digital Inputs and Digital Outputs are optically isolated circuits
with no common path between any channel terminal and another channel, or
between any channel and the LRP830 power. Because they are independent
and floating, the external wiring controls their use. The inputs can be config
-
ured for sensors with a PNP or NPN output. The outputs can be configured
in a Sourcing or Sinking configuration. The examples in Figures 17 through
24 show different connections for common input and output devices.
Inputs
The +IN terminal must be at a higher positive potential than the -IN terminal
for current to be sensed correctly. The voltage range is 4.5 to 30V between
the +IN and the -IN inputs and the maximum current is 25 mA.
Outputs
The output is limited to 30Vdc when off and 500 mA. These are maximum
ratings. A device that operates at 200 mA may destroy the output due to in-
rush current if that current exceeds 500 mA (e.g. an incandescent light). The
inductive "kick" (back EMF from a collapsing magnetic field) when a relay
is released can impose a voltage higher than 30V and destroy the output
transistor (use a backwards diode to clamp the back EMF).
Copyright © 2000 Escort Memory Systems
18 LRP830-Series Long-Range Passive Reader/Writer