User's Manual

Turbo PMAC User Manual
Executing Individual Motor Moves 227
Multiple homing moves can be started together by specifying a list or range of motor numbers with the
command (e.g. HOME1,3 or HOME2..6). Further program execution will wait for all of these motors to
finish their homing moves. Separate homing commands, even on the same line (e.g. HOME1 HOME2)
will be executed in sequence, with the first finishing before the second starts. It is not possible to execute
partially overlapping homing moves from a single motion program.
Note:
Note carefully the difference in syntax between the on-line command and the
buffered command. The on-line command is simply HOME or HM, and it acts on
the currently addressed motor, so the motor number must be specified in front of
the command (e.g. #1HM). In the buffered command, the motor number is part of
the command, following immediately after HOME or HM letters (e.g. HM1).
Homing from a PLC Program
Turbo PMAC PLC programs can command homing search moves by giving on-line commands with the
COMMAND"" statement (e.g. COMMAND"#1HM"). These commands simply start the homing search
move; code must be written to monitor for finishing if that is desired. The motor number must be
specified in the specific command string, or with the ADDRESS#n statement; without this statement,
motor addressing is not modal within PLC programs.
Motion vs. PLC Program Homing
The following table summarizes the differences between homing using motion programs and PLC
programs.
Motion Programs PLC Programs
Program execution point stays on the line
containing the Home command until the
homing move is finished.
The PLC does not automatically monitor
for the start and end of the homing move.
Home command can be combined with
programmed axis moves.
Axis motion can only be performed
through Jog commands. .
The C.S. must be ready to run a motion
program.
The C.S. does not need to be ready to run
a motion program.
Can only home motors defined in the C.S.
running the program.
Can home any motor not defined in a C.S.
presently running a program.
Motors can be homed simultaneously, one
after another, or any combination of the
two. All motors started together must
finish before next action can start.
Motors can be homed in any order. This
includes starting one motor in the middle
of another motor's home move.
The motion program must be started by an
on-line command, a PLC program, or
another motion program.
The PLC can be started by an on-line
command, a PLC program, another
motion program, or automatically at
power-up or reset.
Zero-Move Homing
To declare the current position the home position without commanding any movement, use the HOMEZ
(on-line) or HOMEZn (motion program) command. These are like the HOME command, except that they
immediately take the current commanded position as the home position. The Ixx26 offset is not used
with the HOMEZ command. This no-move homing is useful both for early development, before the true
homing procedure is developed, and for specialized homing routines not supported by Turbo PMAC’s
automatic homing procedures.