Delta Tau GEO BRICK LV User Manual

 

Many of the statements in Turbo PMAC motion programs are modal in nature.  These include move 
modes, which specify what type of trajectory a move command will generate; this category includes 
LINEAR, RAPID, CIRCLE, PVT, and SPLINE.  Moves can be specified either incrementally (distance) 
or absolutely (location) – individually selectable by axis – with the INC and ABS commands.  Move 
times (TA, TS, and TM) and/or speeds (F), are implemented in modal commands.  Modal commands can 
precede the move commands they are to affect, or they can be on the same line as the first of these move 
commands.  

The move commands themselves consist of a one-letter axis-specifier followed by one or two values 
(constant or expression).  All axes specified on the same line will move simultaneously in a coordinated 
fashion on execution of the line; consecutive lines execute sequentially (with or without stops in between, 
as determined by the mode).  Depending on the modes in effect, the specified values can mean, 
destination, distance, and/or velocity (see Trajectory Features section). 

Among Turbo PMAC’s outstanding characteristics are the power and flexibility of its trajectory 
generation algorithms.  These algorithms allow a great variety of difficult maneuvers to be performed, 
and permit you to make your own tradeoffs between ease of use and degree of control.  It is important to 
remember that these trajectories are a series of commanded positions only.  It is up to the servo loops for 
each axis to try to make the actual positions match the commanded positions.  All the times, speeds, 
distances, and profiles discussed in this section are commanded ones, unless otherwise noted. 

The easiest class of moves to make is the linear blended move category.  In this type of move, an axis 
moves toward the target position at a designated speed, accelerating to and decelerating from this speed in 
a controlled fashion.  If more than one move is specified in succession with no pause in between, the first 
move will blend into the second with the same type of controlled acceleration as is done to and from a 
stop.   

Linear blended move mode is the default mode for motion programs.  If in another move mode, the 
program can be put into this mode with the LINEAR statement.  The program can be taken out of 
LINEAR mode with another move mode statement (e.g. CIRCLE1, CIRCLE2, RAPID, PVT, SPLINE). 
It is good programming practice to declare the LINEAR mode in each program, and not rely on the 
default.  The LINEAR statement is equivalent to the RS-274 G-Code G01. 

The destination point of a linear-mode move is specified in the move command itself (e.g. X10Y20).  The 
commanded destination for each axis can be specified as a position relative to the programming origin (if 
the axis is in ABS absolute mode) or with a distance from the last commanded position (if the axis is in 
INC incremental mode).  The program specifies one of these; Turbo PMAC automatically calculates the 
other. 

You can specify either the target velocity (feedrate) for the move, with an F command, or the move time 
with the TM command.  If F is specified, the move time is calculated, and if TM is specified, the feedrate is 
calculated.  The relationship between the two values is reciprocal for a given move distance.  Move-time 
and feedrate values are modal; they affect all subsequent linear (and circle) mode moves until another F 
or TM value is specified in the program.