ACC Programmer's Reference Guide

Chapter 2 35
ZCOM Message Handling
Error Handling
Error Handling
In the normal functioning of ZCOM, transmission errors on messages to
terminal ZLUs are handled by the Mux interface card firmware. The
firmware a lways sends a s tatus back to t he driver after it has processed
a request - retries are handled internally. The driver checks the mode of
the send (i. e., send no wait, report errors, etc.) to determine what to pass
back to the requesting program.
If a p ower failure occurs or the Mux interface card crashes, the driver
receives an interrupt from the operating system. This interrupt causes
thedrivertosendarequesttoZMONtodownloadthefirmwaretothe
particular interface card a nd to perform a full restart sequence (which
also involves re-sending any unacknowledged messages). If the directory
/var/opt/acc/dmp exists, ZCOM will upload the contents of the Mux
card memory and store it i n a file in this directory w henever a Mux card
failure is detected. This provides the ability to analyze firmware failures
which can be particularly valuable during the development of custom
protocols.
For a detailed description of ZCOM C interface routine error codes,
please refer to the ACC Error G uide.