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What is a Channel Watchdog? How can the user application monitor correct function of the firmware operation?


Each Communication Channel in the Dual Port Memory (DPM) offers a dedicated watchdog handling, allowing the netX firmware to monitor the correct processing of the host application and vice versa.

Two 32bit data fields in each DPM communication channel are used for the watchdog handling:

  • ulDeviceWatchdog (DPM Common Control Block)
  • ulHostWatchdog (DPM Common Status Block)

The handling itself simply consist of a copy function which must be cyclically executed by the host application.

The host application has to copy the content from the ulHostWatchdog field to the ulDeviceWatchdog field.

By default, the watchdog is disabled. The first copy automatically activates the watchdog.

From this point the host application has to repeate the copy function once during the configured watchdog time.

The watchdog time can be configured using mailbox packets HIL_SET_WATCHDOG_TIME_REQ, HIL_GET_WATCHDOG_TIME_REQ

If the application does not process the copy and the watchdog time expires, a watchdog hit will be signaled to respective Firmware Communication Channel.

  • Real Time Etherent or Fieldbus Channels will close network connections and stop cyclic data exchange in case of a watchdog hit
  • But the communication firmware will not reset the chip

The watchdog handling can be done by

  1. Plain access to the DP-Memory (e.g. using memcpy)
  2. Using of the cifXAPI function xChannelWatchdog()

Please refer to the DPM Manual and the cifX API Manual for further information.