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Problem statement

In tame testing environments, it's easy to have packet loss rates lower than 1 in a billion. But in electrically noisy environments, it is not feasible to require 0% packet loss between LinuxCNC and a hostmot2 ethernet card. At present, however, a single lost read request or read response packet causes missed realtime deadlines; a lost write packet can also have serious consequences (e.g., loss of the packet that sets the index-enable flag during homing could cause a machine to run into a hard limit)


  1. Allow hm2_eth to work properly even in the presence of low packet loss. "low" is not yet defined, but is perhaps 1/1000 or 1/10000.
  1. Allow hm2_eth to detect high packet loss in a way that can be hooked to the estop chain
  2. Allow the rest of linuxcnc to work properly

Testing Methodology

Linux iptables can simulate packet loss. For higher level testing, a stepper-type configuration can be used without attached hardware beyond the

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Last edited March 28, 2016 12:10 pm by JeffEpler (diff)
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