Rockwell Automation 1756-OF8H ControlLogix HART Analog I/O Modules - Manual (Page 16)

16 Rockwell Automation Publication 1756-UM533C-EN-P - February 2011
Chapter 1 ControlLogix HART Analog I/O Modules
Commands can be accepted from either of two master devices. The controller is
one of the master devices and continuously obtains information from the field
device. The second master can typically be device maintenance, for example a
handheld communicator, as shown below.
Integrated HART Networks
Most transmitters are available with a HART protocol interface. The type of data
available is dependent on the type of instrument.
An example application is a smart mass flowmeter. By using just the standard
mA signal from the flowmeter it provides one field measurement - flow. By using
the mA signal with HART provides additional process information. The
mA signal representing flow is still available. The HART configuration of the
flowmeter can be set for
primary value (PV) being mass flow, secondary value
(SV) being static pressure, third value (TV) being temperature, and
fourth value (FV) being a digital representation of the mA signal.
In addition to these additional process variables, device status is also provided via
HART. Instead of one process variable, the controller sees four process variables,
has a check on the mA signal, and has a reading of device status. HART
connectivity provides all this with no changes to the existing 4…20 mA wiring.
This HART connectivity also provides remote configuration and
troubleshooting of field devices by using software, such as FactoryTalk
AssetCentre or Endress+Hauser FieldCare software.
HART-enabled I/O Modules
The ControlLogix HART analog I/O modules have HART modems built in,
so there is no need to install external HART multiplexors or clip on
HART modems.
Primary Master
Secondary Master
(handheld communicator
as secondary master)
Slave
44219