Lan Bypass Segments; Bypass Watchdog Support; Led Behaviour; Figure 18: Onboard Lan Ports And Bypass Segments - Advantech FWA-5020 User Manual

"Disconnect" mode is typically used to block any traffic until the system has fully
started up and the application SW is in a well defined state allowing to handle traffic
properly.
Connectivity can be auto controlled by a number of system events:

Power Up
Host system is turned on / powers up (DC on)

Power Down
Host system is turned off / powers down (DC off)

Power Reset
Host system is reset or rebooted

Watchdog Start
LAN bypass watchdog is started or strobed for the first time

Watchdog Timeout
LAN bypass watchdog timed out

External Trigger
Global Watchdog Trigger input (dedicated GPIO pin)
In addition to the event driven model, it is also possible to set the connectivity for a
bypass segment via the SW API.

2.5.3.1 LAN Bypass Segments

The FWA-5020 supports four onboard traffic ports which are grouped into 2
bypass segments as shown below:

Figure 18: Onboard LAN ports and bypass segments

2.5.3.2 Bypass Watchdog Support

Each bypass segment is support by an independent watchdog timer. The timer basis
is set to 100ms. Watchdog timeout periods can be set between 100ms and 6553.5
seconds (about 109 minutes).
The FWA-5020 also supports a global watchdog trigger which allows multiple bypass
segments to be controlled at the same time. The global watchdog signal is connected
between the two onboard bypass segments and also to the PCIe extension
connector (for future use).

2.5.3.3 LED Behaviour

Advantech Advanced LAN bypass uses a LED to show the state of a bypass
segment. Usually the bypass LED is implemented as a dual colour LED combined
with a regular LAN port LED. The table below shows the status of the bypass LED,
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FWA-5020 User Manual v01 Copyright 2015 Advantech Co. Ltd. All rights reserved. Page 45