Each SMS Service has a Fail Count that increases by 1 when an invalid SMS message is received or resets to 0 when a valid SMS message is received. If a succession of invalid SMS messages are received, the Fail Count may exceed the SMS Service’s Incoming SMS Fail Limit (defined in the configuration of the SMS Service) and this will cause an alarm to be raised. Any messages received while the Fail Count exceeds the Incoming SMS Fail Limit are disregarded—Geo SCADA Expert makes no attempt to process them as they may be malicious.
Should the Fail Count for an SMS Service exceed the SMS Service’s Incoming SMS Fail Limit, an SMS Command Processor Excessive Failures alarm is raised. The description for the alarm will include:
'SMS Command Processing suspended due to repeated failure(s) to process incoming SMS command(s)'.
If an SMS Command Processor Excessive Failures alarm is raised, you need to investigate the cause of the alarm by examining the entries in the driver log (see Display a Driver Log File in the Geo SCADA Expert Guide to Server Administration). You should be able to use the information in the driver log to determine the source of the messages, which you can then use to investigate whether the messages pose a threat or are simply invalid due to error. For example, invalid messages may be being received because a user is consistently making the same mistake when typing in the text for the SMS.
Once you have discovered the cause of the alarm and have resolved the problem, you will need to clear the alarm by resetting the Fail Count manually. If you do not reset the Fail Count manually, Geo SCADA Expert will continue to disregard incoming SMS messages for the SMS Service (as the alarm will not have cleared and the Fail Count will still be exceeding the Incoming SMS Fail Limit).
You can reset the Fail Count manually when the Fail Count is higher than 0. There is no need to wait for an alarm to be raised.
To manually reset the Fail Count for an SMS Service:
- Log on to Geo SCADA Expert via a User account that has the OPC Data permission (see Allocating Security Permissions in the Geo SCADA Expert Guide to Security).
- In the Database Bar, locate the relevant SMS Service database item and right-click on it to display its context sensitive menu.
- Select the Reset Incoming SMS Command Failure Count option.
The Fail Count is reset to 0.