Troubleshooting
SCADA Troubleshooting
SCADA Troubleshooting in industrial control systems — covering 6 topic areas in the CurryControls.com controls and automation knowledge hub.
Written guides in this section
Full references, procedures, and diagnostic guides published under SCADA Troubleshooting.
Values Frozen On Screen
The HMI shows numbers that are not changing while the plant runs. Whether the controller, the communication driver, the tag server, or the display stopped, and the order to check them in.
7 min readUpdated Sep 5, 2026
Tag Shows Bad Quality
A tag flagged bad or uncertain by the driver. What the quality codes mean, the difference between a device that is not answering and an address that does not exist, and how to clear each.
7 min readUpdated Sep 5, 2026
Alarms Not Annunciating
The condition is real and nothing happened on the screen or the phone: where an alarm can be lost between the controller and the operator, from the alarm bit and the tag quality to the alarm server, the display filter, the shelved and suppressed lists, the audible, and the notifier.
9 min readUpdated Sep 5, 2026
Trend Gaps
Holes in a trend where data should be: a communication loss, a historian that stopped or fell behind, a buffer that filled or never forwarded, compression set too coarse, a renamed tag, or a clock that jumped. Reading the cause from the shape of the gap.
8 min readUpdated Sep 5, 2026
Client Cannot Connect
A workstation, web, or mobile client that cannot reach the SCADA server: the service down, a firewall path closed, a license or session limit, a certificate or name failure, a version mismatch after an update, or expired credentials. Testing each layer.
8 min readUpdated Sep 5, 2026
Duplicate or Missing History
A historian with two records for one moment, or none: a redundant pair both collecting, a buffer that forwarded twice, a tag under two names, a daylight saving shift, or a source that resends on reconnect. Cleaning the record without inventing data.
8 min readUpdated Sep 5, 2026
Topics in this area
Values Frozen On Screen
Values Frozen On Screen — practical reference notes for controls engineers, integrators, and technicians working with scada troubleshooting.
Tag Shows Bad Quality
Tag Shows Bad Quality — practical reference notes for controls engineers, integrators, and technicians working with scada troubleshooting.
Alarms Not Annunciating
Alarms Not Annunciating — practical reference notes for controls engineers, integrators, and technicians working with scada troubleshooting.
Trend Gaps
Trend Gaps — practical reference notes for controls engineers, integrators, and technicians working with scada troubleshooting.
Client Cannot Connect
Client Cannot Connect — practical reference notes for controls engineers, integrators, and technicians working with scada troubleshooting.
Duplicate Or Missing History
Duplicate Or Missing History — practical reference notes for controls engineers, integrators, and technicians working with scada troubleshooting.
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