Understanding Instrument Fail as an attribute as opposed to a state

Note: For information on overriding default configuration settings, see Modify configuration settings.

If values reported from the field device fall outside of the instrument range while Instrument Fail Check is enabled, depending on the configuration, the system does one of two things:

• Sets the point to an Instrument Fail state and sets the Instrument Fail attribute.

• Sets the Instrument Fail attribute only and leaves the point in its last known state.

If the system is configured to set the point to an Instrument Fail state, the alarms generated are part of the "hilo" category. These alarms replace prior "hilo" alarms for the point.

If the system is configured to set the Instrument Fail attribute only, the alarm generated is part of the "instfail" category. This alarm does not override any prior "hilo" alarms, and it co-exists with any prior state alarms for the point. The alarm for instrument fail as an attribute can be inhibited for analog and rate points using the Instrument fail as attribute configuration in the Advanced Database Editor (ADE). A timed inhibition can be set for analog and rate points from easy Extended Operator Station (ezXOS).

Notes: If the system is configured to indicate an instrument failure condition as a Flexible Data Attribute, this instrument failure condition can only be visualized by Control Room Management (CRM) objects. Other graphical objects, such as rt_text, generic_ device, or rt_table cannot show this attribute, but they will display a Stale or Error icon.

If the system is configured to the Instrument Fail attribute only, configuring the Instrument Fail High, Instrument Fail Low, or Instrument Fail RTN states as safety-related states has no effect, because the points will never be in such states.

The following procedure details how to configure the system to represent the point as instrument fail for either state or attribute.

To configure the instrument failure condition as an attribute

1. Navigate to the %DNADataRoot%\RealTime\config\Settings directory, and then either create or open the RealTime_InstrumentFail_Attribute.json file.

2. In the following object, change false to true:

   {

   "RealTime": {

   "INSTR_FAIL_AS_ATTRIBUTE": true

   }

   }

3. Save the file.

4. Restart the RealTime service.

   Note: Configuring INSTR_FAIL_AS_ATTRIBUTE to true overrides the INSTR_FAIL_LASTGOOD configuration. The last good value is used when INSTR_FAIL_AS_ATTRIBUTE is enabled as well as when INSTR_FAIL_LASTGOOD is configured to true.