Precautions For Hart In A Safety System; Configure Hart For Field Device Monitoring - Rockwell Automation Allen-Bradley 1715-AENTR User Manual

Chapter 5 Using 1715 Analog I/O Module Features
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Make sure that your HART field devices support HART command 0 ('read
unique ID') and HART command 3 ('read current and four dynamic variables'),
the 1715 redundant I/O system uses these commands to communicate with the
HART devices.
The 1715 analog input and output modules use HART command #03 to collect
data from the field device as defined by Revision 5 of the HART specification.
The data available from HART enabled field devices is reported to the
application in the AB:1715_ChHART_Struct sub-structure of the modules input
tag.
The structures provide the following:
• Process measurements and measurement status.
• Errors on HART communication seen by the field device.
• Status of the field device.
• Time in milliseconds since the data was last updated.
You can monitor the status of the field device and use this to report diagnostic
errors and manual configuration changes.
The HART data is also available to the user for monitoring purposes via the
HART Device Info tab of the I/O module properties.
IMPORTANT The update rate for HART data from field devices is slower than
the update rate for the 4 mA to 20 mA analog signal itself. HART
data can take up to 4 seconds to update a channel, depending on
the device type and configuration. This is not affected by the
number of channels enabled for HART, but is affected if HART
Pass-Through is in use on the channel.

Precautions for HART in a Safety System

IMPORTANT If you use HART in a safety system, take these precautions:
• Do not use HART variables as the primary initiator for a Safety
• Make sure that HART is disabled for field devices that do not have
• Make sure that the custom data for the device (this is the data

Configure HART for Field Device Monitoring

When an analog module is added to the RSLogix™ application, input, output
and configuration tags for the module are automatically created. The input
tags contain AB:1715_ChHART_Struct sub-structures for HART data. The
configuration tags contain a HartEn variable that is used to enable HART on
individual channels.
Rockwell Automation Publication 1715-UM001J-EN-P - December 2020
Instrumented Function. The HART protocol does not meet the
applicable integrity levels for Safety Instrumented Functions.
a locked configuration. This will prevent the use of HART to
change a device configuration.
provided in response to HART command #03) is used in
accordance with the device manufacturers published
recommendations.