For each SMS Service, there is an internal Fail Count that is used in conjunction with the Incoming SMS Fail Limit (defined in the configuration of an SMS Service, see Define the Number of Times an SMS Service will attempt to Process Messages). The Fail Count increases by 1 each time an invalid SMS message is received via the SMS Pager Channel associated with the SMS Service—invalid messages can be rejected by the Pager Driver or by Geo SCADA Expert. Each valid message causes the Fail Count to reset to 0. If the Fail Count exceeds the Incoming SMS Fail Limit, any incoming SMS messages for that SMS Service are disregarded (although they are logged).
The Fail Limit and Incoming SMS Fail Limit are used to:
- Provide security against ongoing invalid SMS messages (which could be malicious)
- Help prevent resources being wasted on attempts to process invalid SMS messages.
The Fail Limit and Incoming SMS Fail Limit offer greater protection and efficiency. However, they also stop Geo SCADA Expert from processing any valid SMS messages that are received after the Incoming SMS Fail Limit has been exceeded. For example, if the Incoming SMS Fail Limit was set to 3 and 5 invalid SMS messages were received in succession and then a valid SMS message was received, Geo SCADA Expert would only attempt to process the first 3 invalid messages. The fourth invalid SMS message would cause the Fail Count to exceed the Incoming SMS Fail Limit, and so an alarm would be raised. The fifth invalid message and the valid SMS that followed it would not be processed. As a result, the valid SMS would not be processed and so could not cause the Fail Count to be reset. In this situation, the alarm can only be cleared by a user manually resetting the Fail Count (this means that if the Fail Count is exceeded, there is user interaction and investigation into the cause of the invalid SMS messages).
It is possible for the Fail Count to far exceed the Incoming SMS Fail Limit. For example, if the Pager Driver receives a high number of messages that it detects as being invalid SMS messages, it will reject each message. For each rejected message, the Pager Driver will instruct Geo SCADA Expert to increase the count by 1—this may cause the Fail Count to rise significantly above the Incoming SMS Fail Limit, as the Pager Driver will reject each invalid message irrespective of the number of invalid messages received. Geo SCADA Expert is different in that it will only process a set number of invalid messages (the Incoming SMS Fail Limit) before it stops processing messages.
In the following sections, we explain how to view the current value of the Fail Count and how to use the Reset Incoming SMS Command Failure Count action to reset the Fail Count manually:
- Checking the Fail Count for Incoming SMS Commands
- Resetting the Fail Count for Incoming SMS Commands.
If you are seeking help with Clearing an SMS Command Processor Excessive Failures Alarm, you should refer to Resetting the Fail Count for Incoming SMS Commands.