Reference Manual

Turbo PMAC/PMAC2 Software Reference
Turbo PMAC Global I-Variables 46
I17 Rotary Buffer Request Off Point
Range: 0 to 8,388,607
Units: Program lines
Default: 10
This parameter controls how many lines ahead of the executing line the host can provide a PMAC rotary
motion program buffer before it signals that it is not ready for more lines (BREQ line held low,
coordinate system status bit Rotary Buffer Full becomes 1). This status information can be detected
either by polling ?? or PR, by using the interrupt line to the host, or by polling the status register of the
interrupt controller.
If a program line is sent to the rotary buffer, the BREQ line will be taken low (at least momentarily). If
there are still fewer than I17 number of lines in the buffer ahead of the executing line, the BREQ line will
be taken high again (giving the ability to generate an interrupt) and the Rotary Buffer Full status bit will
stay 0. If there are greater than or equal to I17 lines in the buffer ahead of the executing line, the BREQ
line will be left low, and the Rotary Buffer Full status bit will become 1. Normally at this point, the host
will stop sending program lines (although this is not required) and wait for program execution to catch up
to within I16 lines and take BREQ high again.
Note:
On Turbo PMAC, the BREQ line to the interrupt controller reflects the status of
the hardware-selected coordinate system (by JPAN pins FPDn/) if the control-
panel inputs are enabled (I2=0); it represents the status of the software-host-
addressed coordinate system if the control-panel inputs are disabled (I2=1). In
virtually all applications using this feature, the user will want to set I2 to 1 so the
BREQ line reflects the status of the coordinate system to which he is currently
talking. On Turbo PMAC2, the BREQ line always reflects the status of the
software-host-addressed coordinate system.
I18 Fixed Buffer Full Warning Point
Range: 0 to 8,388,607
Units: Long memory words
Default: 10
I18 sets the level of open memory below which BREQ (Buffer Request) will not go true (global status bit
Fixed Buffer Full will become 0) during the entry of a fixed (non-rotary) buffer.
Every time a command line is downloaded to an open fixed buffer (PROG or PLC), the BREQ line will
be taken low (at least momentarily). If there are more than I18 words of open memory left, the BREQ
line will be taken high again (giving the ability to generate an interrupt), and Fixed Buffer Full will stay at
0. If there are I18 words or less, the BREQ line will be left low, and Fixed Buffer Full will become 1.
The number of available words of memory can be found using the SIZE command.
I19 Clock Source I-Variable Number (Turbo PMAC2 only)
Range: 6807, 6857 … 7907, 7957
Units: I-variable number
Default: 7007 (non-Ultralite Turbo PMAC2)
6807 (Turbo PMAC2 Ultralite)
Configuration-dependent (Turbo PMAC2-3U)