Meriam 4150X ATEX I.S. Certified HART Communicator - Manual (Page 19)

15
HART
®
Communications with the 4150 / 4150X
Overview
The 4150 / 4150X HART communicator provides device specific HART communication functions that
allow the user to poll, configure and maintain supported HART field devices. The 4150 / 4150X uses
Universal, Common Practice and Device Specific commands to facilitate communication with a HART
field device. Use the 4150 / 4150X to commission devices, for operational re-configuration needs, or
maintain devices through analog and sensor trim adjustments and many other features.
The 4150 / 4150X will communicate with any HART device through Universal and Common Practice
Commands using the standard Generic DOF (Device Object File) but must have the DOF for a specific
HART device installed before it can execute Device Specific Commands. Consult the large and growing list
of available DOFs at
www.meriam.com for an up to date list of HART devices with device specific support.
The list is found under the Resources tab, Download Center page, by selecting the “Available DOFs” link.
When HART device support for new devices becomes available, the 4150 / 4150X can be easily field
updated via Internet downloads.
Warning: To avoid damage to a PC serial port, do not connect the Unit’s HART leads to an AC powered
HART device while the unit is on AC power and a serial cable is connected to a PC. Meriam recommends
disconnecting the HART leads from the communicator prior to any communication activity.
HART Commands
Three HART command types are used by the 4150 / 4150X to communicate with HART field devices. First,
Universal Commands are primarily used to identify a field device by its model number and tag number and
to read process data from the device. This communication is referred to as “polling”. The 4150 / 4150X can
poll any Hart Device. Second, Common Practice Commands are used for calibration and maintenance
functions that are common to many devices. An example of this would be trims or adjustments for the
devices’ analog outputs. Third, Device Specific Commands are used to handle functions that are unique to a
particular device or manufacturer. Examples of these commands include sensor zero, sensor trim, calibration
curve characterization, density inputs required for calculations made by the HART device or other
configuration functions unique to the specific device.
HART Connections
HART connections are made using two standard banana jacks (3/4” center) located at the top end of the 4150
/ 4150X. Refer to the following diagram. Polarity is not a concern for HART connections, therefore, both
jack collars are black. Meriam supplies a HART lead kit (P/N ZA900529-00014) complete with mini-
grabber connections and a 250 Ω load resistor with each unit.
For low load loops (less than 250 Ω), a 250 Ω resistor may be needed in the loop to insure reliable HART
communications. Meriam supplies a 250 Ω load resistor in the form of a standard adaptor (P/N ZA36821).
Refer to the following diagram for connection details.
4150 with HART ®
HART ® connections are standard
banana jacks (3/4” center)