GMA array

The GMA array is an sppx convenience for processing multi-axis MULTIGOTO movements: it presents the machine's controlled coordinates (with their new/previous values, output flags and angle-reduction results) in a single indexed structure.

sppx only. There is no direct GMA counterpart in .NET. In a .NET postprocessor the multi-axis move is read from the strongly-typed MULTIGOTO command (ICLDMultiGotoCommand) - its Axes collection gives each axis and value - and the register handling that GMA performs in sppx is done through the .NET registers API. See the Access from .NET section of the MULTIGOTO command.

Access from sppx

Use the predefined GMA array to conveniently process multiaxis movement MULTIGOTO command in the technology program and in the mask of the command. GMA array is initialized directly before the MULTIGOTO technology command is processed.

Every item of GMA array corresponds to an controlled coordinate of the machine scheme. Items of the GMA array can be added manually using the Postprocessor generator interface or imported directly from CAM system machine scheme.

Optionally, coordinates can be added to GMA array during postprocessor execution using following operator syntax:

GMA(<AxisName> {,<RegisterName>})

Here AxisName is a legal expression that returns a string. The new coordinate name will be set to AxisName, use it to access the new item. Optional parameter RegisterName is the name of the register associated with the new coordinate.

Example

GMA("AxisXPos")

Use the name of a coordinate to access it's GMA properties:

GMA[<AxisName>].<Property>

Or for masks:

<Axisname>.<Property>

Here AxisName is a legal string expression that must be a valid coordinate name. In the following example the name of the coordinate AxisXPos is used to access the coordinate current value:

GMA["AxisXPos"].Vn ! Vn - coordinate current value

GMA Structure

GMA array item has the following structure:

GMA[<AxisName>].OutFlag
GMA[<AxisName>].Vn
GMA[<AxisName>].Vp
GMA[<AxisName>].Axis
GMA[<AxisName>].Reg
GMA[<AxisName>].TurnCount
GMA[<AxisName>].Dir
  • GMA[<AxisName>].OutFlag is an Integer field that is assigned values 1 or 0. Use this flag to determine whether the coordinate named AxisName is listed in the given MULTIGOTO command. GMA[<AxisName>].OutFlag has the value of 1 (the flag is set) if there is a coordinate named AxisName in the given MULTIGOTO command, otherwise the flag is 0.
  • GMA[<AxisName>].Vn is a Real field and it's value is the new value of the coordinate AxisName set by MULTIGOTO command. Use the Vn field to read or set the new coordinate value.
  • GMA[<AxisName>].Vp is a Real field that contains the value of AxisName coordinate assigned by the previous MULTIGOTO command. Use the Vp field to read or set the previous coordinate value.
  • GMA[<AxisName>].Axis is a String field that is the name of the coordinate and is equal to AxisName. The field is read-only.
  • GMA[<AxisName>].Reg is a String field and it's value is the name of the register associated with the coordinate. The field is read-only.
  • GMA[<AxisName>].TurnCount is an Integer field that is assigned the number of full turns of a rotatable axis. The field is read-only.
  • GMA[<AxisName>].Dir is an Integer value that is assigned +1 if the value of the coordinate is increasing, otherwise it is set to -1. The field is read-only.

Use TurnCount and Dir fields to process the movement of rotatable axes. CAM system passes the movements of rotatable axes in absolute values, whereas some NC-systems accept only values in bound ranges like 0º to 360º or 180º to -180º for those coordinates. Use the Machine axes parameters dialog to define the bounds and ranges parameters of rotatable axes. If angle reduction is defined for a given coordinate then when processing MULTIGOTO command the system will reduce the coordinate value Vn to specified range, assign the TurnCount field the number of full revolutions of the coordinate and set the sign of the Dir field depending on the previous (not reduced) value of the coordinate.

Here are a few examples illustrating how the system initializes the properties of GMA array items when processing MULTIGOTO technology command. Suppose rotatable axis C (AxisCPos) is bound to values from 0º to 360º.

  1. Command:
MULTIGOTO COUNT 4, AxisXPos(18) 80, AxisYPos(20) 19.877,
AxisZPos(22) -200, AxisCPos(24) 0

GMA array for the MULTIGOTO command:

Coordinate name OutFlag Vn Vp Axis Reg TurnCount Dir
AxisXPos 1 80 -//-//- "AxisXPos" "X" -//-//- -//-//-
AxisYPos 1 19.877 -//-//- "AxisYPos" "Y" -//-//- -//-//-
AxisZPos 1 -200 -//-//- "AxisZPos" "Z" -//-//- -//-//-
AxisCPos 1 0 -//-//- "AxisCPos" "C" -//-//- -//-//-

"-//-//-" sign indicates that the values of the properties of coordinates cannot be determined because there is no information of the previous command.

  1. Command:
MULTIGOTO COUNT 1, AxisCPos(24) 270

GMA array for the MULTIGOTO command:

Coordinate name OutFlag Vn Vp Axis Reg TurnCount Dir
AxisXPos 0 80 80 "AxisXPos" "X" -//-//- -//-//-
AxisYPos 0 19.877 19.877 "AxisYPos" "Y" -//-//- -//-//-
AxisZPos 0 -200 -200 "AxisZPos" "Z" -//-//- -//-//-
AxisCPos 1 270 0 "AxisCPos" "C" 0 +1
  1. Command:
MULTIGOTO COUNT 2, AxisZPos(22) 250, AxisCPos(24) -745

GMA array for the MULTIGOTO command:

Coordinate name OutFlag Vn Vp Axis Reg TurnCount Dir
AxisXPos 0 80 80 "AxisXPos" "X" -//-//- -//-//-
AxisYPos 0 19.877 19.877 "AxisYPos" "Y" -//-//- -//-//-
AxisZPos 1 250 -200 "AxisZPos" "Z" -//-//- -//-//-
AxisCPos 1 335 270 "AxisCPos" "C" 2 -1

In the last example the system applied angle reduction for the AxisCPos(C) coordinate. The value passed by CAM system "-745 º" is reduced to the range from 0º to 360º by the following rules:

TurnCount = |(Vn' - Vp') \ 360|
TurnCount = |(-745 -270) \ 360| = 2
Dir = Sgn(Vn'-Vp')
Dir = Sgn(-745 -270) = -1
Vn = Vn' - (Vn' \ 360)*360, if Vn' > 360
Vn = Vn' - (Vn' \ 360)*360 + 360, if Vn' < 0
Vn = -745 - (-745\360)*360 + 360 = 335

Vn' - the current not reduced value of the coordinate, Vp' - previous not reduced value of the coordinate.

The following is an example of a simple MULTIGOTO command program that uses the GMA array:

program MultiGoto
  ! Use the GMA fields to assign
  ! respective registers their new values
  if GMA["AxisXPos"].OutFlag>0 then
    X = GMA["AxisXPos"].Vn
  if GMA["AxisYPos"].OutFlag>0 then
    Y = GMA["AxisYPos"].Vn
  if GMA["AxisZPos"].OutFlag>0 then
    Z = GMA["AxisZPos"].Vn
  if GMA["AxisCPos"].OutFlag>0 then
    C = GMA["AxisCPos"].Vn
  ! Output the formed values into the NC-program
  OutBlock
end

See also