Jump to content
OMRON Forums

PPMAC Absolute Position Initialization Problem


eloew61
 Share

Recommended Posts

We are using an ACC-14E interface to a PPMAC to provide absolute position for two axes via synchro to digital (S/D) converters. When the PPMAC is first powered on, PLC1 is executed which performs a homez on both motor axes using the following code:

 

Motor[AZ_MOTOR_NUMBER].pAbsPos=ACC14E[0].DataReg[0].a

Motor[EL_MOTOR_NUMBER].pAbsPos=ACC14E[0].DataReg[3].a

Motor[AZ_MOTOR_NUMBER].AbsPosFormat=$00200F08;

Motor[EL_MOTOR_NUMBER].AbsPosFormat=$00200F08;

Motor[AZ_MOTOR_NUMBER].AbsPosSF=1.0;

Motor[EL_MOTOR_NUMBER].AbsPosSF=1.0;

 

Coord[1].PosRollOver[0]=360.0;

Coord[1].PosRollOver[0]=360.0;

 

homez AZ_MOTOR_NUMBER;

homez EL_MOTOR_NUMBER;

 

This routine correctly initializes the absolute position about 20% of the time. At other times, the position is exactly twice what it should be. When this occurs, acc14r0, acc14r1, acc14r3 and acc14r4 all contain the correct 16 bit angles; however #1p and #2p contain twice the angle, respectively. Re-running PLC1 from the IDE command line fixes the problem. I have attached before and after IDE screenshots of this.

PMAC_init_4.thumb.png.9a0e05a3991a4036ab295b6ace6be4c3.png

PMAC_init_5.thumb.png.5374f535f3a3c852abbe93b9919b1a20.png

Link to comment
Share on other sites

  • Replies 5
  • Created
  • Last Reply

Top Posters In This Topic

Note that it is not necessary to set these structure elements in your PLC:

Motor[n].pAbsPos

Motor[n].AbsPosFormat

Motor[n].AbsPosSF

Coord[n].PosRollOver[0]

 

as these are saved elements in Power PMAC. If you set these in your project and save them they will be permanent. Your PON PLC will be simpler. Also note that if bit 4 of Motor[x].PowerOnMode is set then this could be interfering with the homez commands your PLC.

Link to comment
Share on other sites

Note that it is not necessary to set these structure elements in your PLC:

Motor[n].pAbsPos

Motor[n].AbsPosFormat

Motor[n].AbsPosSF

Coord[n].PosRollOver[0]

 

as these are saved elements in Power PMAC. If you set these in your project and save them they will be permanent. Your PON PLC will be simpler. Also note that if bit 4 of Motor[x].PowerOnMode is set then this could be interfering with the homez commands your PLC.

 

steve.milici, thanks for your advice. Motor[x].PowerOnMode is set to 0 for both motor 1 and motor2.

Link to comment
Share on other sites

This could be a problem with the power-on PLC that initializes the ACC-14E. This may not be ready when your 'homez' PLC runs. Put a timer delay at the beginning of this PLC.

 

Forgive my ignorance, but will a "dwell" command work in this context?

Link to comment
Share on other sites

No - the "dwell" command is intended for motion programs only. In PLCs you must use a timer delay. Below is code for a timer delay. Put it in a subprogram and use it like this in you top level PLC programs:

 

Call timer(0.1); // delay 0.1 seconds.

 

 

// This subprogram creates a timed delay of duration specified in the argument "time" [seconds]

open subprog timer (time)

local EndTime;

EndTime = Sys.Time + time;

do {}

while (EndTime > Sys.Time);

close

Link to comment
Share on other sites

Guest
This topic is now closed to further replies.
 Share


×
×
  • Create New...