Rockwell Automation 1770-HT8 SMART TRANSMITTER - Manual (Page 12)

Chapter
1
1-1
Introducing the Smart Transmitter Interface
This chapter provides an overview of the Smart Transmitter Interface
products, a brief introduction to the HART protocol and a description of
the different system architectures which can be implemented. It also
describes the features and benefits of using the Smart Transmitter Interface
and lists some of the products that are compatible with the 1770-HT1,
1770-HT8 and 1770-HT16.
The Smart Transmitter Interface products provide a communication
interface between Allen-Bradley PLC controllers or host computers and
HART field devices (transmitters, transducers and actuators). These
products give host processors access to the digital information encoded
with the 4-20 mA analog process control signal. The digital information
can be passed to and from the host processor using either a remote I/O
(RIO) or an RS-232C port.
A Smart Transmitter Interface consists of one Communications Controller
(1770-HT1), and one or more Terminal Blocks (1770-HT8 or 1770-HT16).
These products can be mounted on a DIN rail in a control cabinet and the
field wiring brought directly to the Terminal Blocks.
1770ĆHT1 Communications Controller
The 1770-HT1 Communications Controller receives commands from a
host processor and passes them on, via the 1770-HT8/16 Terminal Blocks,
to HART field devices. Responses from the HART field devices go
through the Terminal Blocks to the Communications Controller and then
on to the host processor.
The Communications Controller communicates through its Remote I/O or
RS-232C port to the host processor. The combination of hardware and
software used by the host determines which port is used.
Use the Remote I/O port (labelled RIO in Figure 1.1) with the following:
a programmable controller as host processor using ladder logic to
perform block transfer reads and writes. On the DH+ network the
programmable controller can connect to a computer running software
applications, such as ControlView, to monitor and supervise the ongoing
processes.
Product Overview