PMAC Quick Reference Guide M167 is related to the master/slave relationship set through Ix05 and Ix06. It contains the present number of counts the master. To read this register in counts: P167 = M167 / (I108*32) or P167 = M167 / (I107*32) M169->D:$0046 ; #1 Compensation correction Calculated leadscrew compensation correction according to actual position (M162) and the leadscrew compensation table set through the define comp command. To read this register in counts: P169 = M169 / (I108*32) M172->L:$082B ; #1 Variable jog position/distance (counts) Contains the distance for the J=* command. Example:
M172=2000 J=* ;Jog to position 2000 encoder counts M173->Y:$0815,0,24,S ; #1 Encoder home capture offset (counts) Contains the home offset from the reset/power-on position. This is important for the capture/compare features. Example: If (M117=1) P103=M103-M173 ; Captured position minus offset endif M174->Y:$082A,24 ; #1 filtered actual velocity (1/[Ix09*32] ; cts/servo cycle) These registers contain the actual velocities averaged over the previous 80 real-time interrupt periods (80*[I8+1] servo cycles); this is useful for display purposes. To read this register in cts/msec:
P174 = M174 * 8388608 / (I109 * 32 * I10 * (I160+1)) M175->D:$0840 ; #1 following error (1/[Ix08*32] cts) Following error is the difference between motor desired and measured position at any instant. When the motor is open loop (killed or enabled), following error does not exist and PMAC reports a value of 0. 32 * I108 M167 * M175 M169 M164 M162 M161 176 P − + + − = To read this register in counts: P176 = M175 / (I108*32) Homing Search Moves If PMAC is not using an absolute feedback sensor that will keep a point of reference on the machine, the axis should be homed before running a motion program or JOG commands.
If a home search procedure is not performed after power-up\reset, PMAC will consider the power-up\reset position as the zero point reference. The flag channel used by Ix25 must match the position feedback channel used by Ix03 (indirectly from the conversion table). Programming PMAC 41 I-Variable Description I-Variable Description Ix03 Motor x Position Address Ix26 Motor x Home Offset Ix20 Motor x Jog/Home Acceleration Time I902, I907,.. Encoder 0 Capture Control (PMAC 1 only) Ix21 Motor x Jog/Home S-Curve Time I903, I908,..
Encoder 0 Flag Select (PMAC 1 only) Ix23 Motor x Homing Speed & Direction Ix25 Motor x Flag Address Description M-Variable Description M-Variable ENC capture/compare position register Mx03 Fault input status Mx23 ENC 3rd channel input status Mx19 Desired-velocity-zero bit Mx33 HMFL input status Mx20 In-position bit Mx40 -LIM input status Mx21 Home-complete bit Mx45 +LIM input status Mx22 Encoder home capture offset (counts) Mx73