User's Manual

Turbo PMAC User Manual
Making your Application Safe 217
The following table summarizes the different commands that can be used to stop motion and their
attributes:
Command Scope Begin
Immed?
Stop on
Path?
Stop at
Prog Pt?
Decel
Rate
Notes
J/
Motor Yes –- No Ixx19-
21
A
C.S. Yes No No Ixx15 No easy restart
<CTRL-A>
Global Yes No No Ixx15 No easy restart
Q
C.S. No Yes Yes TA, TS Finishes calculated moves
<CTRL-Q>
Global No Yes Yes TA, TS Finishes calculated moves
/
C.S. No Yes Yes TA, TS End of currently executing
move*, undoes blending
H
C.S. Yes Yes No Isx95 Similar to %0
<CTRL-O>
Global Yes Yes No Isx95 Similar to %0
\
C.S. Yes Yes No Ixx17/
Isx95
Acts as H command if
outside of lookahead
K
Motor Yes No No
—
Must stop program first
<CTRL-K>
Global Yes No No
—
Must stop program first
Program Checksums
Firmware Checksum
Turbo PMAC continually computes the checksum of its internal program (firmware) as a background
task. Each time it has computed the checksum, it compares this value to a reference register in memory
(obtainable with the CHECKSUM command) that has been manually entered with the correct value. Turbo
PMACs shipped from the factory are preloaded with the correct reference value for that firmware version
at the factory.
If Turbo PMAC detects a mismatch between its calculated checksum and the reference checksum, it sets
global status bits (bits 12 and 13 of X:$000006 – accessible with the ??? command) and stops
performing any checksum operations. This leaves the calculated value frozen in the running checksum
register X:$001080. Turbo PMAC does take any other action in the event of a firmware checksum error;
it is up to the host or a Turbo PMAC PLC program to decide what action to take.
When a Turbo PMAC is upgraded to new firmware by replacement of the PROM IC in standard CPU
sections or downloading of new firmware into the flash EEPROM IC in Option CPU sections, the
reference checksum value will be updated automatically for the new firmware.
User-Program Checksum
Turbo PMAC continually computes the checksum of the fixed user program buffers as a background task.
Each time it has computed the checksum, it compares this value to the checksum value that was computed
the last time one of these buffers was closed, stored in X:$001090.
If Turbo PMAC detects a mismatch between these two checksums, it sets a global status bit (bit 13 of
X:$000006 – accessible with ???) and stops performing any program or firmware checksum operations
(communications checksum is independent), freezing the running checksum value in X:$001080. It does
not shut down operation automatically. It is up to the host or a Turbo PMAC PLC program to decide
what action to take if there is a checksum error.