Of Operation 2

AS-INSTALLED RECORD KEEPING

A HART configurator also facilitates record keeping. As-installed device configuration data can be stored in memory or on a disk for later archiving or printing.

Device Status and Diagnostics

Most HART field instruments provide both status information and diagnostic information. The HART protocol defines basic status information as information that is included with every message from a field device. Basic status information enables the host application to immediately identify warning or error conditions detected by the field device. Status messages also enable the user to differentiate between measurements that are outside sensor or range limits and actual hardware malfunctions. Examples of status messages are:

• 
  Field device malfunction
  
• 
  Configuration changed
  
• 
  Cold start
  
• 
  More status available
  
• 
  Analog output current fixed
  
• 
  Analog output saturated
  
• 
  Nonprimary variable out of limits
  
• 
  Primary variable out of limits
  

HART instruments can implement extensive, device-specific diagnostics. The amount and type of diagnostic information is determined by the manufacturer and varies with product and application. Diagnostic information can be accessed using the HART communication protocol.
Host applications using DD files can interpret and display diagnostic information. Applications not using DD technology may require product- specific software modules to interpret diagnostic information.
Many manufacturers offer special software applications for their own products. Some modules allow you to customize for specific products. Manufacturers of valve actuators have made extensive use of this capability to provide preventative and predictive diagnostic information that greatly enhances the value of their products as compared to conventional actuators.
Several software applications are available that provide continuous communication with field devices using a HART-compatible multiplexer and HART I/O (see Multiplexers on page 26). These applications provide real-time monitoring of status and diagnostic information.

Connecting a PC to a HART Device or Network
PCs are commonly used for HART host applications for configuration and data acquisition. A specially designed device (Table 5) allows the HART network to be connected to the RS232C serial port or PCMCIA slot of a PC (Figure 16).