Why are some LonWorks devices propagating "device escape codes 0x7D" to the network ? (KB155)

Question Detail
Why are some LonWorks devices propagating "device escape code 0x7D" after power up?
These escape codes can be seen in the protocol analyzer.

Devices which include the remote debug kernel will notify the debugger about each reset by making use of "device escape" messages. In NodeBuilder 1.5, the debug kernel is added to a device's Neuron C application by using the library #include . In NodeBuilder 3.0 and newer, the debug kernel is added automatically to the Development Target.
This is a desirable thing to have for debugging, but it is also a dangerous thing to have in production devices, especially since the debugger is not available on-site.

In NodeBuilder 1.5, you should make sure to remove the #include directive from your device's source code prior to generating a production build. In NodeBuilder 3.0 and newer, you should make sure to use the Release Target for your production builds.
It is also possible to leave the debug kernel in and selectively disable the reset message by using #pragma debug no_reset_event. You can also turn off all event notification using #pragma debug no_event_notify.

There is nothing special about these messages, they should show up as normal messages in a LonTalk Protocol Analyzer. However, the debug kernel uses a message image which resides in EEPROM and this EEPROM space is the same space as the application data so it is not checksummed. Thus, it is possible for one to modify this memory (application bug, corruption or Network Management write message) such that the message image contents get corrupted. Certain forms of corrupted messages (specifically, illegal protocol version number) are not displayed by LonTalk Protocol Analyzers.

Related Products
  • Control Module
  • FT 3120/FT 3150
  • LonManager Protocol Analyzer 1.0
  • LTM-10A
  • Network Architecture
  • Neuron C
  • Neuron Chips
  • NodeBuilder 1.5
  • NodeBuilder 3.0
  • NodeBuilder 3.1
  • PL 3120/PL 3150
  • PSG-3/PSG-20
Was this article helpful?
0 out of 0 found this helpful
Have more questions? Submit a request


Powered by Zendesk