Request Timeout and Request Timeout Extension for Advanced Drivers

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You can use the ClearSCADA Server Configuration Tool (under Global Parameters/Drivers) to define the maximum amount of time permitted for a driver to complete a request. By defining a maximum time, you ensure that the driver can abort a request that is taking too long to complete. This prevents requests from taking an excessive amount of time to complete (or becoming 'stuck' and unable to complete).

There are two driver request timeouts:

• Request Timeout — The driver must start to perform the request within this period. If the request is still pending after this period, the request is aborted and fails. However, if the request is active when the Request Timeout time expires, additional time is allowed for the request to complete. This additional amount of time is the Request Timeout Extension.

• Request Timeout Extension — An additional amount of time that is added to the Request Timeout. The Request Timeout Extension is only used if the request is active at the time the Request Timeout expires. For example, if the Request Timeout is 600 seconds, and after 600 seconds the request is active (the driver is in the process of performing the request), the request is allowed an additional period to complete. The additional time period is the amount of time defined for the Request Timeout Extension. If the request has not completed after this extended period, the request is aborted and fails.

Typically, the default settings of 10 minutes, with a 5 minute extension are adequate. However, certain requests such as a file transfer or download configuration may take longer due to slow communication links, or very large files or outstations. For these types of request, you may need to increase the timeouts.

Requests that are aborted and fail due to a timeout are logged in the Event Journal.

Following we have real world examples of how the timeouts work showing excerpts from the DNP3 driver log:

• Request completed within the Request Timeout period

• Driver receives from DBServer a request to disable alarms for a point in an outstation (DNP3 protocol). This involves file/configuration transfer.

02-AUG-2010 00:23:27.571 [Main] Received Disable Alarms request (Id:63763) for "S.BONDI.SP0028 BALMAIN.SITE_.PWR01.Authority Supply Fail Hours"

• The process is completed within 10 min (600 sec, default Request Timeout period)

02-AUG-2010 00:23:27.574 [Main] Sending Disable Alarms request (Id:63763) for "S.BONDI.SP0028 BALMAIN.SITE_.PWR01.Authority Supply Fail Hours" to "*System.Comms.S.DNP IP.SetChannel 0091.Channel A"02-AUG-2010 00:23:27.574 [Channel A #2823932] Activated Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SITE_.PWR01.Authority Supply Fail Hours" in scanner02-AUG-2010 00:23:27.578 [Channel A #2823932] Adjusting Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SITE_.PWR01.Authority Supply Fail Hours" to timeout in 30164 ms02-AUG-2010 00:23:27.621 [Channel A #2823932] Adjusting Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SITE_.PWR01.Authority Supply Fail Hours" to timeout in 37183 ms02-AUG-2010 00:23:30.847 [Channel A #2823932] Adjusting Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SITE_.PWR01.Authority Supply Fail Hours" to timeout in 30151 ms02-AUG-2010 00:23:31.777 [Channel A #2823932] Adjusting Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SITE_.PWR01.Authority Supply Fail Hours" to timeout in 30154 ms02-AUG-2010 00:23:31.815 [Channel A #2823932] Adjusting Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SITE_.PWR01.Authority Supply Fail Hours" to timeout in 30161 ms02-AUG-2010 00:23:31.865 [Main] Received reply (Successful) from scanner to Disable Alarms request (Id:63763) for "S.BONDI.SP0028 BALMAIN.SITE_.PWR01.Authority Supply Fail Hours"

• Request started within the Request Timeout Period and completed within the Request Timeout Extension Period

• Driver receives from DBServer a request to disable alarms for a point in an outstation (DNP3 protocol). This involves file/configuration transfer.

02-AUG-2010 00:24:08.096 [Main] Received Disable Alarms request (Id:63963) for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Rotation"

• Driver starts the process within 10 min (600 sec, default Request Timeout period)

02-AUG-2010 00:34:07.837 [Main] Sending Disable Alarms request (Id:63963) for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Rotation" to "*System.Comms.S.DNP IP.SetChannel 0091.Channel A"02-AUG-2010 00:34:07.837 [Channel A #2823932] Activated Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Rotation" in scanner02-AUG-2010 00:34:07.841 [Channel A #2823932] Adjusting Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Rotation" to timeout in 30164 ms02-AUG-2010 00:34:07.875 [Channel A #2823932] Adjusting Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Rotation" to timeout in 37183 ms

• As the process doesn't end within 10 mins, a Request Timeout Extension Period of 5 mins is granted (300 sec, default Request Timeout Extension period). It ends successfully within the extended period.

02-AUG-2010 00:34:08.096 [Main] Extending time out of Disable Alarms request (Id:63963) for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Rotation" by 300 sec02-AUG-2010 00:34:10.570 [Channel A #2823932] Adjusting Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Rotation" to timeout in 30151 ms02-AUG-2010 00:34:12.139 [Channel A #2823932] Adjusting Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Rotation" to timeout in 30154 ms02-AUG-2010 00:34:12.181 [Channel A #2823932] Adjusting Disable Alarms request for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Rotation" to timeout in 30161 ms02-AUG-2010 00:34:12.226 [Main] Received reply (Successful) from scanner to Disable Alarms request (Id:63963) for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Rotation"

• Request not started within 10 min (timeout)

• In this case, the queue of messages is full, and the requested process don't start within 10 min.

02-AUG-2010 00:24:08.251 [Main] Received Disable Alarms request (Id:63964) for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Selection"02-AUG-2010 00:34:08.251 [Main] Timed out Disable Alarms request (Id:63964) for "S.BONDI.SP0028 BALMAIN.SP0028.WELCNTL_.Control Well Selection" (Overall)

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