Efficient Plant July 2018 - 20

feature | maintenance strategies

2

TRIAL AND ERROR

Use of trial and error to solve a control-system problem can be very helpful.
The best approach is to change only one variable at a time and observe the
effect it has on the issue. When using this method, be sure to document the change
and result with each trial. Otherwise, you could find yourself after, say, performing
15 trials, trying to remember the result of the third one-to no avail.
The trial-and-error method works best for issues that can be repeated rapidly.
For slower issues, such as those that are time dependent, it's possible to
attempt several changes with each trial and record the result. Minimize
the number of changes in each trial and make no more than two or
three changes at a time. If a trial with multiple changes resolves the
issue, then you can independently test the two or three changes to
determine which is the root cause. Keep in mind when changing
multiple variables at a time, they could be dependent upon each
other and further complicate troubleshooting attempts.

Successful troubleshooting
starts with a good grasp of the issue.

3

LOG DATA

Computer log files are a good place to begin troubleshooting
if a control-system issue involves any servers, Windows-based
HMIs, or other devices that keep log files. Every Windows computer has a tool
called Event Viewer that can be found in the Administrative Tools of the control
panel. While the Event Viewer contains a substantial amount of information that is
likely irrelevant to the issue, it's necessary to sort and filter. Often the "System" and
"Application" logs provide the most value. Certain applications may also maintain their
own log files, which can provide invaluable troubleshooting insight.
Many PLCs also have the ability to log data points and create trend charts on the
fly. This method is effective for any timing or PLC-code-related issues. Set up a trend
to capture relevant I/O (input/output) points and internal PLC tags that are used in
the logic, then reproduce the issue and see what the trend looks like. When using
this method, pay attention to the rate at which data is being collected as it could alter
results or provide a false view of the situation.
For intermittent issues, setting up some type of a data logger may also help to capture the issue when you're not physically present. If the operators are able to observe
the issue, have them note the exact time when the issue occurs so you can go back and
examine the log files.

20

| EFFICIENTPLANTMAG.COM

JULY 2018


http://www.EFFICIENTPLANTMAG.COM

Table of Contents for the Digital Edition of Efficient Plant July 2018

Editorial
Implementations
Find Gold In Sustainable Manufacturing
Troubleshoot Control Systems Effectively
Automation Accelerates Beer Production
Lubed Chains Live Long Lives
SAP: Use These Tools For PM Compliance
Protect Your Site From Cyber Attacks
Build The Value Of Your CM Program
Choose The Correct Acclerometer
On The Floor
Intelligent Design Process Delivers For Substation
Solution Focus
Old Compressor Gets New Lease On Life
Products
Index
Showcase
Seeking Reliability
Efficient Plant July 2018 - Cover1
Efficient Plant July 2018 - Cover2
Efficient Plant July 2018 - 1
Efficient Plant July 2018 - 2
Efficient Plant July 2018 - 3
Efficient Plant July 2018 - 4
Efficient Plant July 2018 - 5
Efficient Plant July 2018 - Editorial
Efficient Plant July 2018 - 7
Efficient Plant July 2018 - Implementations
Efficient Plant July 2018 - 9
Efficient Plant July 2018 - Find Gold In Sustainable Manufacturing
Efficient Plant July 2018 - 11
Efficient Plant July 2018 - 12
Efficient Plant July 2018 - 13
Efficient Plant July 2018 - 14
Efficient Plant July 2018 - 15
Efficient Plant July 2018 - 16
Efficient Plant July 2018 - 17
Efficient Plant July 2018 - Troubleshoot Control Systems Effectively
Efficient Plant July 2018 - 19
Efficient Plant July 2018 - 20
Efficient Plant July 2018 - 21
Efficient Plant July 2018 - Automation Accelerates Beer Production
Efficient Plant July 2018 - 23
Efficient Plant July 2018 - 24
Efficient Plant July 2018 - 25
Efficient Plant July 2018 - 26
Efficient Plant July 2018 - Lubed Chains Live Long Lives
Efficient Plant July 2018 - 28
Efficient Plant July 2018 - 29
Efficient Plant July 2018 - SAP: Use These Tools For PM Compliance
Efficient Plant July 2018 - Protect Your Site From Cyber Attacks
Efficient Plant July 2018 - Build The Value Of Your CM Program
Efficient Plant July 2018 - Choose The Correct Acclerometer
Efficient Plant July 2018 - On The Floor
Efficient Plant July 2018 - 35
Efficient Plant July 2018 - Solution Focus
Efficient Plant July 2018 - 37
Efficient Plant July 2018 - 38
Efficient Plant July 2018 - 39
Efficient Plant July 2018 - Old Compressor Gets New Lease On Life
Efficient Plant July 2018 - 41
Efficient Plant July 2018 - Products
Efficient Plant July 2018 - 43
Efficient Plant July 2018 - 44
Efficient Plant July 2018 - 45
Efficient Plant July 2018 - Index
Efficient Plant July 2018 - Showcase
Efficient Plant July 2018 - Seeking Reliability
Efficient Plant July 2018 - Cover3
Efficient Plant July 2018 - Cover4
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