Rockwell Automation 1770-HT8 SMART TRANSMITTER - Manual (Page 67)

Communicating with the Smart
Transmitter Interface
Chapter 4
Communicating with the Smart Transmitter
Interface
4-2
Figure 4.1
System Data Flows with a Smart Transmitter Interface
90065
HART Response
or
HART Burst Data
HART
Field
Devices
DF1 Commands
Programmable
Controller
Host Computer
DF1 Responses
BTW Data
All packets on this link
are Smart Transmitter Interface
packets
RIO
BTR Data
RSĆ232C
HART Poll
4Ć20 mA
Loop
All packets on this link
are HART packets
All packets on this
link are DF1 packets
Data Routing In Poll and Response Mode
A Smart Transmitter Interface operating in the Poll and Response mode
receives packets as Block Transfer Write (BTW) data from a
programmable controller and forwards those packets as HART polls to the
field device. When the field device responds, the Smart Transmitter
Interface routes that response to the programmable controller as data in a
Block Transfer Read (BTR). The Smart Transmitter Interface receives
similar packets from, and sends them to the host processor on the RS-232C
link in the form of DF1 commands and responses instead of Block Transfer
Writes and Reads.
Data Routing in Burst Monitor Mode
In Burst Monitor mode the Smart Transmitter Interface watches specified
channels for HART burst data from field devices and places this data in a
Burst Data table. Programmable controllers request this data via a BTW to
the Smart Transmitter Interface which returns the data from the Burst Data
Table in a BTR. Host computers request and receive this data via DF1
commands and responses rather than BTWs and BTRs.