March 2021
Installation, Operation and Maintenance Manual
MDE 254 Rev. 1
HART Protocol Previews8
Section 5: HART Protocol Previews
5.1 HART Wirings
According to HART specification, the following working modes are available: point to point,
split range, multidrop.
The selection is done according to the Table below by means of the dip switches SW5 on the
HART module.
Table 1.
SW5 pin 1 SW5 pin 2 SW5 pin 3 SW5 pin 4 Connections Mode
OFF OFF ON ON Point to Point
OFF OFF ON ON Split Ranging
ON ON OFF OFF Multidrop
NOTE: The factory configuration is POINT to POINT.
• POINT TO POINT
In Point to Point mode, the 4 - 20 mA signal is used to communicate one process variable,
while additional process variables, configuration parameters, and other device data are
transferred digitally using the HART Protocol. The 4 - 20 mA analog signal is not affected
by the HART signal and can be used for control. The HART communication digital signal
gives access to secondary variables and other data that can be used for operations,
commissioning, maintenance and diagnostic purposes.
Figure 4
• SPLIT RANGING
Split Range Control is a single control loop divided into two or more independent final
control elements such as valves acting in different directions or in different steps. The field
devices are connected in series in the same 4 - 20 mA current loop, each field device must
have a unique polling address, different from each other in the range 0 - 15.
Figure 5
4 - 20 mA
4 - 20 mA
HART
MAINS
ICON3000
ICON3000
ICON3000
MAINS
MAINS
HART
4 - 20 mA
4 - 20 mA
HART
Interface
HART
Interface