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PVT move and X:$B0 Bit 11 Block Request


BrianSS
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Hello,

 

I am currently running a PVT move using the following program:

OPEN PROG 31 CLEAR
P7030=((M345*P7433*P4036)+((M362/(I308*32))/M391))
P3361=P7030
P3360=1
P3341=P4430
P3340=1
DWELL(0)
IF(P7030-0.01  IF(P4430    P7630=6
   GOTO1      						  
 END IF
END IF
DWELL(0)
DWELL(0)
CALL1 X(P4430)S(P7030)V(P4434)A(P4436)D(P4438)P(0.73)
N1
DWELL(0)
CLOSE

 

The motion variables are all being sent from the PLC. Occasionally the axis will start the move and not get to the desired position and X:$B0 Bit 11 Block Request will be on. I have taken I5313 up to 10, this did not seem to help.

 

The moves are typically a few inches for this axis and I have seen it on numerous different moves.

 

 

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Here is PROG 1 (called from PROG 31 above):

 

; Variables to pass arguments to subroutine
; Note that the variable numbers here are fixed
#define AArg						Q101											; Variable to pass A argument
#define DArg						Q104											; Variable to pass D argument
#define PArg						Q116											; Variable to pass P argument
#define SArg						Q119											; Variable to pass S argument
#define VArg						Q122											; Variable to pass V argument
#define XArg						Q124											; Variable to pass X argument

; Variables for general-purpose use
#define ProgDist				Q150											; Signed distance for move
#define Dir							Q151											; Direction of move
#define AccDist					Q152											; Mag of distance for accel
#define DecDist					Q153											; Mag of distance for decel
#define AccTime					Q154											; Total time for accel
#define DecTime					Q155											; Total time for S decel
#define AccSTime				Q156											; Time for half of S accel
#define DecSTime				Q157											; Time for half of S decel
#define Apeak						Q158											; Mag of top accel reached
#define Dpeak						Q159											; Mag of top decel reached
#define ApeakTime				Q160											; Time at top accel reached
#define DpeakTime				Q161											; Time at top decel reached
#define ReachSpeed			Q162											; True (1) if move hits prog speed
#define Seg1Dist				Q163											; Signed distance of 1st seg
#define Seg1EndVel			Q164											; Signed end vel of 1st seg
#define Seg2Dist				Q165											; Signed distance of 2nd seg
#define Seg2EndVel			Q166											; Signed end vel of 2nd seg
#define Seg3Dist				Q167											; Signed distance of 3rd seg
#define Seg3EndVel			Q168											; Signed end vel of 3rd seg
#define Seg4Dist				Q169											; Signed distance of 4th seg
#define Seg4EndVel			Q170											; Signed end vel of 4th seg
#define Seg5Dist				Q171											; Signed distance of 5th seg
#define Seg5EndVel			Q172											; Signed end vel of 5th seg
#define Seg6Dist				Q173											; Signed distance of 6th seg
#define Seg6EndVel			Q174											; Signed end vel of 6th seg
#define Seg7Dist				Q175											; Signed distance of 7th seg
#define TopVTime				Q176											; Time at top speed
#define Vpeak						Q177											; Peak speed if less than prog
#define OldAbsIncMode		Q178											; Saved to restore at end
#define FourSecDist			Q179											; Distance in 4 sec at top speed

; Subroutine used by multiple other programs to execute move using PVT segments
OPEN PROG 1 CLEAR
READ(X,S,V,A,D,P)
ProgDist=XArg-SArg																; End minus Start, signed qty
Dir=ABS(ProgDist)/ProgDist												; +1 or -1 (0 if no distance)

; Make sure S-curve percentage is in proper range
IF(PArg<0.04) PArg=0.04														; Minimum 4% S-curve
IF(PArg>0.96) PArg=0.96														; Maximum 96% S-curve


; LIMITS ACCEL RATE SO THAT EACH ACCEL SLICE DOES NOT EXCEED 4000 ms
IF (((VArg/AArg)*1000*PArg/2)>4000)								; Calculates S-Curve AccTime
AArg=VArg*1000*PArg/(4000*2)
ENDIF
IF (((VArg/AArg)*1000*(1-PArg))>4000)							; Calculates Linear AccTime
AArg=VArg*1000*(1-PArg)/4000
ENDIF

; LIMITS DECEL RATE SO THAT EACH DECEL SLICE DOES NOT EXCEED 4000 ms
IF (((VArg/DArg)*1000*PArg/2)>4000)								; Calculates S-Curve DecTime
DArg=VArg*1000*PArg/(4000*2)
ENDIF
IF (((VArg/DArg)*1000*(1-PArg))>4000)							; Calculates Linear DecTime
DArg=VArg*1000*(1-PArg)/4000
ENDIF

; Compute distances needed to get to and from full speed
AccDist=VArg*VArg/AArg/2													; Dist mag to reach full speed
DecDist=VArg*VArg/DArg/2													; Dist mag to decel to zero


IF(AccDist+DecDist	Vpeak=VArg																			; Top speed is programmed
ReachSpeed=1																		; Flag for future logic
ELSE																							; No full-speed segment
Vpeak=SQRT(ABS(ProgDist)/((1/AArg+1/DArg)/2))		; Lower peak speed mag
AccDist=Vpeak*Vpeak/AArg/2											; Dist mag to reach peak speed
DecDist=Vpeak*Vpeak/DArg/2											; Dist mag to decel to zero
ReachSpeed=0																		; Flag for future logic
ENDIF

AccTime=Vpeak/AArg																; Total accel time in sec
AccSTime=AccTime*PArg/2														; In each half of S, in sec
ApeakTime=AccTime*(1-PArg)												; Time at peak accel, in sec
Apeak=Vpeak/(AccTime-AccSTime)										; Magnitude of peak accel
Seg1EndVel=Dir*Apeak*AccSTime/2										; Segment 1 signed end velocity
Seg1Dist=Dir*Apeak*AccSTime*AccSTime/6						; Segment 1 signed distance
Seg2EndVel=Seg1EndVel+Dir*Apeak*ApeakTime					; Seg 2 signed end velocity
Seg2Dist=(Seg1EndVel+Seg2EndVel)*ApeakTime/2			; Seg 2 signed distance
Seg3EndVel=Dir*Vpeak															; Segment 3 signed end velocity
Seg3Dist=Dir*AccDist-Seg1Dist-Seg2Dist						; Segment 3 signed distance

IF(ReachSpeed=1)																	; Segment at programmed speed?
Seg4Dist=ProgDist-Dir*(AccDist+DecDist)					; Signed distance at speed
Seg4EndVel=Dir*Vpeak														; Signed end velocity
TopVTime=Seg4Dist/Seg4EndVel										; Total time at top speed, in sec
ENDIF

DecTime=Vpeak/DArg																; Total decel time in sec
DecSTime=DecTime*PArg/2														; In each half of S, in sec
DpeakTime=DecTime*(1-PArg)												; Time at peak decel, in sec
Dpeak=Vpeak/(DecTime-DecSTime)										; Magnitude of peak decel
Seg7Dist=Dir*Dpeak*DecSTime*DecSTime/6						; Segment 7 signed distance
Seg6EndVel=Dir*Dpeak*DecSTime/2										; Segment 6 signed end vel
Seg5EndVel=Seg6EndVel+Dir*Dpeak*DpeakTime					; Segment 5 signed end vel
Seg6Dist=(Seg5EndVel+Seg6EndVel)*DpeakTime/2			; Seg 6 signed distance
Seg5Dist=Dir*DecDist-Seg6Dist-Seg7Dist						; Segment 5 signed distance

BLOCKSTART																				; Beginning of step sequence
INC(X)																						; Specify X moves by distance
PVT(AccSTime*1000)																; Set move mode and time in msec
X(Seg1Dist):(Seg1EndVel)													; 1st half of S-curve accel
PVT(ApeakTime*1000)																; Time at peak accel in msec
X(Seg2Dist):(Seg2EndVel)													; Peak accel segment
PVT(AccSTime*1000)																; Time in 2nd half of S-curve
X(Seg3Dist):(Seg3EndVel)													; Segment to reach top speed
IF(ReachSpeed=1)																	; Segment at programmed speed?
WHILE(TopVTime>4)																; Too long for 1 PVT move
	FourSecDist=Seg4EndVel*4											; Distance in 4 sec at top speed
	PVT4000																				; Set 4-sec move
	X(FourSecDist):(Seg4EndVel)										; Constant speed move for 4 sec
	TopVTime=TopVTime-4														; Time remaining at top speed
	Seg4Dist=Seg4Dist-FourSecDist									; Distance remaining at top speed
ENDWHILE
IF(TopVTime>.0011)															; If Seg4 Move time is > 1.1 msec
	PVT(TopVTime*1000)														; (Remaining) time at top speed
	X(Seg4Dist):(Seg4EndVel)											; (Remaining) top-speed segment
ELSE
  Seg5Dist=Seg5Dist+Seg4Dist 										; Add skipped Seg4Dist to Seg5Dist
ENDIF
ENDIF
PVT(DecSTime*1000)																; Time in 1st half of decel S-curve
X(Seg5Dist):(Seg5EndVel)													; 1st half of S-curve decel
PVT(DpeakTime*1000)																; Time at peak decel
X(Seg6Dist):(Seg6EndVel)													; Peak decel segment
PVT(DecSTime*1000)																; Time in 2nd half of decel S-curve
X(Seg7Dist):0
BLOCKSTOP

RETURN
CLOSE

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Please describe more your comment "Occasionally the axis will start the move and not get to the desired position".

 

How far off is the motor from the desired position?

 

If your motor does not reach the position, perhaps your tuning is inadequate. Please see this post about tuning for some guidelines on tuning.

 

The move that this axis makes is not always the same. Sometimes it is a 6 inch move, other times it only needs to move a few inches. I have seen it stop at seemingly random spots during the moves.

 

I believe the axis is tuned fairly well and I am not seeing any significant following error. The only thing I can see is that when it stops I have the Block request bit on this axis.

 

One of the moves it made was a move from 21.4" to 20", and it stopped ~20.75". The "rest" position for this axis is 21.5", so when we took it out of automatic (all axis' go to "rest" position) and the move command was re-issued, it succesfully moved from 21.5" to 20". So, by changing the start point by 0.1", the axis got to it's desired position.

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We are happy to help you, but I think this will take more troubleshooting than is appropriate for the forum. In order for us to best help you, please call the Technical Support Hotline at 818-717-5656, 8 am to 5 pm PST.

 

Please also go into PeWin, click "PMAC Resources" then "View CPU Resources" and then take a screenshot of that window. Please email it to me. You can access my email address by clicking on my username and then clicking on "Send CharlesP an Email". Thanks!

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