NAMUR NE 107 Standard for Modern Instrumentation Diagnostics

NAMUR NE 107 is a standard adhered to by manufacturers during the design and fabrication of instruments. NAMUR NE 107 provides status signals that communicate clear messages and remedies.  These status signals or diagnostic codes are categorized into four standard icons and colors making it easier for users to comprehend them irrespective of the manufacturer of the instrument:

• Function check – low severity, short-lived invalid signal (for diagnostic codes prioritization, function check is considered as priority 2 by NAMUR).
• Maintenance required – low severity, valid signal however the function will drop or come to an end, such as the end of a temperature sensor’s lifetime (for diagnostic codes prioritization, maintenance is considered priority 3 by NAMUR).  
• Out of specification – medium severity, the instrument is operating beyond the acceptable range (for diagnostic codes prioritization, out of specification is considered priority 4 by NAMUR).
• Failure – high severity, invalid signal due to a glitch or a malfunction in the sensor/instrument (for diagnostic codes prioritization, failure is considered priority 1 by NAMUR).  

Severity in this case signifies the impact of a specific incident on a system whereas priority is used to decide the order in which defects should be fixed.

With the above information, the maintenance personnel can get a clear direction on how they can troubleshoot and fix the problem before the instrument deteriorates to complete breakdown.

A Green diagnostic code signifies a healthy instrument. Orange means the instrument is undergoing a functional check, so the signal is invalid. Blue indicates that the instrument signal is valid, but maintenance is required soon. Yellow signifies that conditions may have caused an out of specification state and hence an uncertain signal. Lastly, Red represents a failure instrument providing an invalid signal and requires an immediate maintenance.

Modern instruments/smart instruments have in-built diagnostics and condition monitoring to help with maintenance and cut down on plant downtime i.e. they are self-diagnostic devices.

Typically NAMUR 107 data is sent over 4-20 mA HART, Wireless HART, Fieldbus, Ethernet/IP, etc. as alarm message or a health-status signal from a smart instrument in the field.

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• 4-20 mA Transmitters (2-wire, 3-wire and 4-wire Types)
• CAMAC (IEEE-583) Modular Instrumentation Standard
• Installation Considerations of an Orifice Plate Flow Sensor