hi! i see a topic of absolute encoder support arises rather regularly. i've been playing with mitsubishi J2 super sscnet servo drives for quite some time and finally i have a working PCI controller. as J2S series motors feature absolute encoders i've made a quick and dirty hack to support them in linuxcnc. here's how it works:
- when initializing drives the controller reads 2 absolute encoder values: 16 bit full-turn counter and a 17 bit 1-rev counter. then it sets drive's initial commanded position to "turns*enc_resolution+counter" - the driver reports that value to linuxcnc as a "motor-pos-fb" - when homing procedure is executed it sets "motor_offset" values. i've modified the emcPositionSave() funcion to save those "motor_offsets" instead of "pos_fb" on exit, so when linuxcnc is restarted a correct position is maintained even if axes are shifted while powered off - to eliminate homing i've added a "halui.joint.N.set-homed" pins which. when set to true, just execute SET_JOINT_HOMED_FLAG(joint, 1) without performing a homing procedure - upon linuxcnc startup a script is executed which checks if absolute encoder data is valid (it is battery backed and can be lost) and if so it sets "homed" flag using "set-homed" pins that works for me as a proof of concept, and i really enjoy a 15 seconds startup time from power-on button to ready-to-mill, but i'm wondering if someone else will find the feature useful and if it's worth it to implement in a proper way... anyone? thanks /dmitry ------------------------------------------------------------------------------ Find and fix application performance issues faster with Applications Manager Applications Manager provides deep performance insights into multiple tiers of your business applications. It resolves application problems quickly and reduces your MTTR. Get your free trial! https://ad.doubleclick.net/ddm/clk/302982198;130105516;z _______________________________________________ Emc-developers mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-developers
