Rockwell Automation 1794-OE8H FLEX I/O HART Analog Modules User Manual - Manual (Page 23)

Publication 1794-UM063A-EN-P - March 2006
About the FLEX I/O HART Analog Modules 1-7
How to Use the
HART Capabilities Before using the HART capabilities, be sure that:
• the I/O module and the associated field device are working properly in
the analog 4 to 20 mA mode.
• the I/O module is configured for 4 to 20 mA range.
• the field device is HART capable.
• no more than one HART field device is connected to each channel.
• input filtering is set to a valid (defined) value.
HART Implementation
Overview The FLEX I/O HART modules act as intelligent HART multiplexers.
Basically, the module learns which HART devices are attached to its channels
and then routes HART messages, as appropriate, between the HART field
devices and the flexbus. Since the HART modules act as intelligent HART
multiplexers, HART commands can be issued to the HART modules
themselves.
Communication on the flexbus occurs between the adapter and the HART
module. The adapter converts these messages to the appropriate network
format for communication with the controlling processor. The controlling
processor gets its command from the user program, storing the responses in
its memory.
Processor
User Program
Adapter FLEX I/O
HART I/O
Module HART
Field Device
Command
Response
For Example,
ControlNet
Flexbus 4 to 20 mA