- Using HART
- How to Choose HART Products
- Device Commissioning
- Configuration
- Integration
- Calibration
- Wire Length & Capacitance
Device Commissioning
Device Commissioning
HART-based instruments have several features that significantly reduce the time required to fully commission a HART network or loop. Less time spent in device commissioning can result in substantial cost savings.
Device commissioning includes the time and cost-saving features:
- Streamlined and centralized device verification
- Easy loop integrity check
- As-installed record keeping
After commissioning, devices need to undergo configuration and calibration prior to use.
Device Verification
Before installation, manufacturers usually enter device tags and other identification and configuration data into each field instrument. This information is usually provided when the device is ordered. After installation, the instrument identification, the tag and descriptor, can be verified either on the workbench or in the control room using a device configurator, which can be a handheld communicator or PC using a modem connected to the device or to the 4-20mA loop.
Some field devices provide information on their physical configuration. For example the devices may deal with wetted materials, ratings or limits of different types.
Physical and other configuration data can be verified in the control room. The verification process is important for safety and in conforming to governmental regulations and ISO quality requirements.
The commissioning process can be further streamlined by connecting a PC-based configuration application to each HART loop. This can be done by integration with the control system or by using one of the many available HART multiplexing I/O systems. With this centralized approach, there is no need to move the configuration device from one termination point to the next while commissioning all devices on the network.
Loop Integrity Check
Once a field instrument has been identified and its configuration data confirmed, the analog loop integrity can be checked using the loop test feature, which is supported by many HART-enabled devices. The loop test enables the analog signal from a HART transmitter to be fixed at a specific value.
This fixed value verifies loop integrity and ensures a proper connection to support devices such as indicators, recorders, and DCS displays. This approach ensures a proper physical connection among all network devices.
Additional integrity can be achieved if the analog value is compared to the digital value being reported in a device. For example, someone might have provided an offset to the 4-20mA analog value that has not been accounted for in the control system. By comparing the digital value of the Primary Variable to the analog value, loop integrity can be verified.
As-Installed Record Keeping
Many HART configurators also facilitate record keeping. As-installed device configuration data can be stored in memory or on a disk for archiving or printing. This facilitates record keeping compliance and provides a documented trail of the configuration to simply device replacement.
Next, let’s look at Device Configuration.