Low Controller Performance - ABB IRC5 Operating Manual

3 Troubleshooting by fault symptoms

3.3 Low controller performance

3.3 Low controller performance
Description
The controller performance is low, and seems to work irrationally.
If the controller is not responding at all, proceed as detailed in section
not responding on page
Consequences
These symptoms can be observed:
Possible causes
The computer system is experiencing too high load, which may be due to one, or
a combination, of the following:
Recommended actions
1
2
3
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43.
• Program execution is sluggish, seemingly irrational and sometimes stalls.
• Programs containing too high a degree of logical instructions only, causing
too fast program loops and in turn, overloads the processor.
• The I/O update interval is set to a low value, causing frequent updates and
a high I/O load.
• Internal system cross connections and logical functions are used too
frequently.
• An external PLC, or other supervisory computer, is addressing the system
too frequently, overloading the system.
Action
Check whether the program contains logical
instructions (or other instructions that take "no
time" to execute), since such programs may
cause the execution to loop if no conditions
are fulfilled.
To avoid such loops, you can test by adding
one or more WAIT instructions. Use only short
WAIT times, to avoid slowing the program
down unnecessarily.
Make sure the I/O update interval value for
each I/O board is not too low. These values
are changed using RobotStudio.
I/O units that are not read regularly may be
switched to "change of state" operation as
detailed in the RobotStudio manual.
Check whether there is a large amount of cross
connections or I/O communication between
PLC and robot system.
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Info/illustration
Suitable places to add WAIT instructions
can be:
• In the main routine, preferably
close to the end.
• In a WHILE/FOR/GOTO loop,
preferably at the end, close to the
ENDWHILE/ENDFOR etc. part of
the instruction.
ABB recommends these poll rates:
• DSQC 327A: 1000
• DSQC 328A: 1000
• DSQC 332A: 1000
• DSQC 377A: 20-40
• All others: >100
Heavy communication with PLCs or
other external computers can cause
heavy load in the robot system main
computer.
Operating manual - Troubleshooting IRC5
3HAC020738-001 Revision: AA
Controller