Docking Calibration

The Docking window provides the software tools needed to manage an instrument calibration program based on docking calibrators.  A docking calibrator is a piece of calibration equipment that is typically used in the field to test and adjust instruments.  It is characterized by the ability to communicate with a host computer, typically via a serial data link,  to acquire its calibration procedures and to return completed calibration data  to the  computer.  Some docking calibrator models have been especially designed to facilitate calibration of HART instruments.

In the Docking window, you assemble instrument calibration "routes" that are collections of instruments you wish to be calibrated by a single calibrator.  You build the Route according to your selection criteria.  Route definitions remain in the database for as long as you wish.  With a click of your mouse, routes are directly downloaded to an intelligent calibrator via a serial cable.  The download calibration procedures include instrument ID's, test points, accuracies, and setup and wrapup advisory prompts.

Bring the calibrator back to the Base Station as often as you like, to upload the test results collected to date.  Route status displays in the Docking window show you the status of all instruments downloaded to the calibrator so that you can track the progress of the route.  Docking requires optional Docking CalLib software tailored for the types of docking calibrators that you choose. 

Manual Docking

This method allows you to employ all of the calibration management features of the Docking window with any process calibrator.  Rather than directly connecting to a calibrator, a route is "downloaded" to a printed report.  For each instrument, the report includes key instrument parameters, calibration set-up and wrap-up advisory text, and test point values for the pre-assigned cal scheme.  You record field test results in the fill-in-the-blanks spaces provided  in the test point table.  A manual upload function steps you through the entry of the recorded data into Base Station.  Route status displays help you track progress of the route.

Directed Calibration

This method can be used when your Base Station computer is in close proximity to your calibration activity.  When you select an instrument for Directed Calibration, Base Station steps you through the calibration procedure with instructions displayed on the monitor.  You enter test data for each test point, as requested by the computer.  Error calculations and test results are displayed immediately.  

Manual Calibration

Even if you had not scheduled a calibration using a Route or had not performed a Directed Calibration, Base Station can still record data from any manual calibration you may perform.  Depending on the calibration equipment you choose, you may need to record field calibration data on paper for transport to the Base Station.  If your calibrator can store test results in memory and display them on demand, then no paper is necessary.  Base Station provides a special manual calibration data entry feature that takes you step by step through the entry of your field generated test data.

HART Instrument Calibration

Zero and span is the traditional test performed on conventional and smart instruments alike to gauge the overall accuracy of the device.  Zero and span calibration is analogous to using the zero and span buttons on the instrument to fine tune the operational characteristics.  The 4-20mA test and calibration are used to validate and adjust the accuracy of a smart transmitter's digital-to-analog signal conversion circuits.  Base Station also supports the testing and trimming of the sensor input of a smart transmitter.   Comprehensive support for smart instruments also includes the ability to invoke a special zero trim function found in certain gauge pressure and differential pressure transmitters and some flow meters.

The Cornerstone HART Comm window is the point of access to the instrument self test and to all other device specific tests and diagnostic capabilities.  These functions, along with the ability to change range and other configuration parameters, may be very effectively used to complement an existing control system.  For many functions, you can digitally interrogate and analyze the instrument, even while it remains in service in the loop.  A monitor window supplements this diagnostic access with the ability to present a graphic or tabular real-time display of the current output of the instrument.  For HART devices, any reportable values may be graphed in any combination you specify.  Complete interpretation of instrument specific data and test results is provided if a ModLib for that instrument is installed in the Cornerstone system.

Calibration Record Types

For any of the calibration methods available, a history record is generated based on the type of calibration performed:

Calibration Data

As appropriate for the calibration record type, the following data is stored for each calibration event:

Calibration Schemes

Each instrument in the database is assigned a named Cal Scheme that defines:

Calibration Methods

Error Calculations

You can set up Base Station to perform either of two types of error calculations:

You set up which of the five error types determine pass/fail for your instrument population.

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Specifications subject to change without notice.
This site was last updated on 17 May 2005.