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Added: 7a8
**Also make sure to discard any packet that has arrived too late (recv() to blackhole before sending read request?)

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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