There are several types of data or information that can be communicated from a HART-enabled device. This includes:

• Device data
• Supplier data
• Measurement data
• Calibration data

When this data is integrated with control, asset management or safety systems, you are able to improve plant operations, lower cost and increase plant availability.

The following is a summary of data items available for communication between HART Devices and a Host.

Process Variable Values

• Primary Process Variable (analog) - 4-20 ma current signal continuously transmitted to host
• Primary Process Variable (digital) - Digital value in engineering units, IEEE floating point, up to 24 bit resolution
• Percent Range - Primary Process Variable expressed as percent of calibrated range
• Loop Current - Loop current value in milliamps
• Secondary Process Variable 1 - Digital value in engineering units available from multivariable devices
• Secondary Process Variable 2 - Digital value in engineering units available from multivariable devices
• Secondary Process Variable 3 - Digital value in engineering units available from multivariable devices

Commands From Host to Device

• Set Primary Variable Units
• Set Upper Range
• Set Lower Range
• Set Damping Value
• Set Message
• Set Tag
• Set Date
• Set Descriptor
• Perform Loop Test - Force loop current to specific value
• Initiate Self Test - Start device self test
• Get More Status Available Information

Codes vary by manufacturer/device

Status and Diagnostic Alerts

• Device Malfunction - Indicates device self-diagnostic has detected a problem in device operation
• Configuration Changed - Indicates device configuration has been changed
• Cold Start - Indicates device has gone through power cycle
• More Status Available- Indicates additional devices status data available
• Primary Variable Analog Output Fixed - Indicates device in fixed current mode
• Primary Variable Analog Output Saturated - Indicates 4-20mA signal is saturated
• Secondary Variable Out of Limits - Indicates secondary variable value outside the sensor limits
• Primary Variable Out of Limits - Indicates primary variable value outside the sensor limits

Device Identification

• Instrument Tag - User defined, up to 8 characters
• Descriptor - User defined, up to 16 characters
• Manufacturer Name (Code) - Code established by HCF and set by manufacturer
• Device Type and Revision - Set by manufacturer
• Device Serial Number - Set by manufacturer
• Sensor Serial Number - Set by manufacturer

Calibration Information for 4-20mA Transmission of Primary Process Variable

• Date - Date of last calibration, set by user
• Upper Range Value - Primary Variable Value in engineering units for 20mA point, set by user
• Lower Range Value - Primary Variable Value in engineering units for 4mA point, set by user
• Upper Sensor Limit - Set by manufacturer
• Lower Sensor Limit - Set by manufacturer
• Sensor Minimum Span - Set by manufacturer
• PV Damping - Primary Process Variable Damping Factor, set by user
• Message - Scratch pad message area (32 characters), set by user
• Loop Current Transfer Function - Relationship between Primary Variable digital value and 4-20mA current signal
• Loop Current Alarm Action - Loop current action on device failure (upscale/downscale)
• Write Protect Status - Device write-protect indicator