Perle Systems Perle IOLAN DS1 - Manual (Page 137)

137
Channels
Digital Input
Overview
When the channel is set for digital input, it monitors voltage or current. Note that the internal jumpers
must match the software setting and must be set to Input, which is the default; see
Digital I/O
Module on page 198 to find out how to set the internal jumpers.
Functionality
The Digital input channels allow you to configure the following options:
z You can choose to remember the last state change, or latch, that occurred. Your options are to
latch (remember) when the state changes from inactive to active or active to inactive.
z You can choose to invert the signal, which is useful if your sensor is wired in such a way that
closed is actually inactive, whereas closed is normally considered active.
z You can also configure an alarm trigger and clear mode based on whether the Digital input is
active or inactive, sending a syslog message and/or SNMP trap when the alarm is triggered or
cleared.
In an industrial freezer warehouse example, a D4 is used to monitor the open door sensor, so that
every time a freezer door is opened, an alarm is triggered and a syslog message is sent to syslog,
where the monitoring application notes the time.
Device Server
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Monitoring
Application
Network
Industrial
Freezers
Input
Input D4
Digital I/O