Applicable Systems
WinCC
Symptoms
The SCADA system reports a variable timeout. A tag or variable has not updated within the configured time.
Possible Causes
- PLC scan time increased delaying tag updates
- Communication bandwidth insufficient for tag count
- Variable configuration incorrect
Troubleshooting Steps
- Step 1: Check the PLC scan time
Scan time is within the expected range - Step 2: Verify the communication bandwidth utilization
Bandwidth is adequate - Step 3: Check the variable configuration and timeout setting
Settings are correct
How to Reset
To reset: Resolve the variable timeout, then clear the alarm in WinCC.
Source: Siemens WinCC SCADA Manual, Siemens AG
Category: SCADA