User's Manual

PMAC User Manual
Basic Motor Moves 131
Buffered Program Command
The homing search move can also be commanded from within a motion program with the HOMEn
command, where n is the motor number. This command specifies a motor; unlike other motion program
commands that specify an axis move. In a motion program, the PMAC automatic program sequencing
routines monitor for the end of the move. When the move is successfully completed, program execution
continues with the next command.
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 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
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
This table summarizes the differences between homing using Motion programs and PMAC PLC
programs.
Motion vs. PLC Program Homing
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 monitor for the start and end of the homing
move automatically.
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. running a program.
Motors can be homed simultaneously, one after another,
or any combination of the two.
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 Ix26 offset is not used with
the HOMEZ command.