Timeout alarms

When commands are sent to a record, a timeout period is required to give the device time to perform the operation. If the operation is not performed within this period, a timeout alarm is generated.

Note: Rate records are typically flow measuring devices with no control capabilities; therefore, rate records do not have this functionality.

Command Failure Timeout Alarming

For status and multistate records, the timeout period for command failure (in seconds) is configured through the Cmd Failure Timeout field on the Output tab for the Row Edit dialog box. This is the maximum period of time for a command to succeed. After the time period has passed, the system issues a failure alarm. The state that the device changes to is likely not the final state, but the fact that a change has occurred indicates that the commanded action is taking place. A typical value would be three to five seconds, but this is device dependent. If the device does not change state within the specified period, the system generates an alarm.

If a command can not be sent to the record due to communication problems, the system generates an alarm and logs the event.

Command Timeout Alarming

For analog and rtstring records, the timeout period for commands (in seconds) is configured through the Command Timeout field on the Output tab in the Row Edit dialog box. Because analog values do not immediately stop at the setpoint, analog records also have a Setpoint Tolerance value. A setpoint is reached when the value is within the tolerance boundary (the setpoint value plus or minus the Setpoint Tolerance value).

The operation of the instrument plays an important role in determining the correct timeout period. Generally, the correct timeout period will be arrived at by trial and error in the testing of a commanded output.

If a command can not be sent to the record due to communication problems, an alarm is generated and the event is logged. All generated alarms are cleared from the alarm summary upon acknowledgement.