On 3/7/13 10:12 , Daniel Rogge wrote: >> But surely it gets set to the correct value by the gearlever >> microswitch approximately 1mS later? > > If you have a microswitch on your gearlever!
Good example Daniel! Ok, now I'm thinking about a piece of hardware that has some persistent state, such as your gearchanger. If the hardware *does* have sensor feedback, then the driver and/or HAL circuitry for that hardware has no need for persistent HAL objects. If the hardware does *not* have sensor feedback, then persistent values may be helpful. They may also be harmful - if you change the state of the hardware while LinuxCNC is off, the persistent value that LinuxCNC remembers next time you start it will be wrong. The tool in the spindle on nonrandom toolchanger machines has this second behavior. While LinuxCNC is up, it keeps track of which tool is in the spindle (assuming, of course, that you tell it with M6). When you restart LinuxCNC, it resets the spindle tool to T0 (which means "no tool" on nonrandom tc machines). (Note that random tc machines remember what tool's in the spindle, by storing this information in the tool table.) -- Sebastian Kuzminsky ------------------------------------------------------------------------------ Symantec Endpoint Protection 12 positioned as A LEADER in The Forrester Wave(TM): Endpoint Security, Q1 2013 and "remains a good choice" in the endpoint security space. For insight on selecting the right partner to tackle endpoint security challenges, access the full report. http://p.sf.net/sfu/symantec-dev2dev _______________________________________________ Emc-developers mailing list Emc-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-developers
