Many analog points support limit tuning. When supported, you can use the Tune Limits check box to define whether operators can tune a point’s alarm limits.
Tuning allows operators whose User Accounts are allocated the Tune Limits permission (see Allocating Security Permissions in the ClearSCADA Guide to Security) to temporarily alter the point’s alarm limits, using the Tune Alarm Limits pick action. (Unless those limits are assigned Time Profiles—you cannot tune any limits that vary in value according to Time Profiles (see Specify any Alarm Limit Profiles).)
Use the feature to tune alarm limits during exceptional circumstances, for example, in bad weather conditions when a flood situation is known to exist—the alarm limits of a point can be tuned to help prevent unnecessary alarms being raised.
Example:
An error detected on some monitoring equipment is giving inaccurate readings for a particular analog point. As engineers are aware of the situation, there is no need to raise alarms, unless the point value changes unexpectedly or raises a genuine alarm.
To avoid unnecessary alarms being raised for the point, the alarm limits are tuned so that ClearSCADA ignores the inaccurate readings.
Once the equipment has been repaired, the tuning is revoked.
ATTENTION: With points on outstations that support configuration downloads, the action of tuning a point’s limits triggers ClearSCADA to download configuration to the outstation on which that point is located (see Downloading Configuration Changes in the ClearSCADA Guide to Core Configuration).
If you choose not to allow the Tune Limits feature to be used, the alarm limits configured on the Point Form remain in force.
To define whether a point’s limits can be tuned:
- Display the Form for the analog point that you want to configure.
- Select the Analog Point tab.
(If you are configuring this feature for another point that uses analog-type processing, select the appropriately named <Point Type> tab. If you are configuring separate server-based limit tuning, select the Master Station Alarm Limits tab.) - Either:
- Clear the Tune Limits check box if users are not permitted to tune the point’s limits.
The alarm limits configured on the Point Form will be used by ClearSCADA, and cannot be temporarily overridden.
Or:
- Select the Tune Limits check box to allow the analog point’s limits to be tuned.
- Ensure that the point’s Tune Limits security permission is suitably set (see Allocating Security Permissions in the ClearSCADA Guide to Security).
Users with the Tune Limits security permission will be able to use the Tune Alarm Limits pick action to temporarily alter the point’s alarm limits.
(If the analog points on your system use Master Station Alarm Limits, and tuning is enabled for those limits, use the Tune M/S Alarm Limits pick action to tune the ‘master station’ limits.)
- Clear the Tune Limits check box if users are not permitted to tune the point’s limits.
- Save the configuration.
Further Information
For information about which tuned alarm limit settings are retained following a 'Copy', 'Convert To', or 'Create Instance' procedure that impacts on a point with tuned limits, see Tune Alarm Limits.