Rockwell Automation 1794-OF8IH FLEX Isolated Input/Output HART Analog Modules - Manual (Page 40)

Publication 1794-UM065B-EN-E - September 2010
28 Input, Output and Configuration of the FLEX I/O HART Analog I/O Modules
configuration words. The number of read words or write words can be 0 or
more.
The length of each I/O module’s read words and write words vary in size
depending on module complexity. Each I/O module will support at least 1
input word or 1 output word. Status and configuration are optional, depending
on the module.
I/O Structure Output data is received by the adapter in the order of the installed I/O
modules. The output data for slot 0 is received first, followed by the output
data for slot 1, and so on up to slot 7.
Input data is sent by the adapter. The first word is the Adapter status word.
This is followed by the input data from each slot, in the order of the installed
I/O modules. The input data from slot 0 is first after the status word, followed
by input data from slot 1, and so on up to slot 7.
Fault State Data The FLEX I/O HART modules provides storage for alternate module output
data during communication faults or processor idle state. This fault state data
assures that a known output will be applied to the output devices during the
previously mentioned modes.
The processor or scanner software must include the means to specify this fault
state data for each module. If applicable, this data is sent in the configuration
block, see page 13.
Device Actions Device actions include:
• Communication fault behavior
• Idle state behavior
• Input data behavior upon module removal
Communication Fault Behavior
You can configure the response to a communication fault for each I/O
module in its system. Upon detection of a communication fault, the module
can:
• Leave the module output data in its last state (hold last state)
• Reset the module output data to zero (reset)
• Apply fault state data to the module output