Reference Manual

PMAC 2 Software Reference
PMAC On-Line Command Specification 215
synchronous M-variable assignments that can be stored in the lookahead buffer. Because
these are evaluated at lookahead time, but not actually implemented until move execution
time, they must be buffered. This section of the buffer must be large enough to store all of
the assignments that could be made in the lookahead distance. Synchronous M-variable
assignments are not made during backup, so there is no need to reserve memory to store
assignments for the backup distance as well as the lookahead distance.
Memory Requirements: For each synchronous M-variable assignment PMAC is told to
reserve space for in the lookahead buffer, PMAC will reserve two 48-bit words of memory.
There are no performance penalties for making the lookahead buffer larger than required, but
this does limit the amount of PMAC memory free for other features.
A lookahead buffer is never retained through a power-down or board reset, so this command
must be issued after every power-up/reset if the lookahead function is to be used.
To erase a lookahead buffer and free up the memory for other use, issue a DELETE
LOOKAHEAD command, or reset the card.
PMAC will reject the DEFINE LOOKAHEAD command, reporting an ERR003 if I6 = 1 or 3,
if any lookahead buffer exists, or if a GATHER buffer exists. Any existing lookahead buffers
and gather buffers must be deleted before a lookahead buffer can be defined.
DEFINE ROTARY
Function
Define a rotary motion program buffer
Scope
Coordinate-system specific
Syntax
DEFINE ROTARY{constant}
DEF ROT{constant}
where:
• {constant} is a positive integer representing the number of long words of memory to
be reserved for the buffer
Remarks
This command causes PMAC to create a rotary motion program buffer for the addressed
coordinate system, allocating the specified number of long words of memory. Rotary buffers
permit the downloading of program lines during the execution of the program.
The buffer should be large enough to allow it to hold safely the number of lines you
anticipate downloading to PMAC ahead of the executing point. Each long word of memory
can hold one sub-block of a motion program (i.e. X1000 Y1000 is considered as two sub-
blocks). The allocated memory for this coordinate system’s rotary buffer remains resident
until the buffer is deleted with DELETE ROT.
Note:
PMAC will reject this command, reporting an ERR003 if I6=1 or 3, if
any ROTARY buffer exists for a lower numbered coordinate system,
or if a LOOKAHEAD or GATHER buffer exists. Any of these
buffers must be deleted first. ROTARY buffers must be defined from
high-numbered coordinate system to low-numbered coordinate system
and deleted from low-numbered coordinate system to high-numbered
coordinate system.
Example
DELETE GATHER ; Ensure open memory