Rockwell Automation 1794-ASB/E Remote I/O Adapter Module User Manual - Manual (Page 35)

Chapter
3
Publication 1794ĆUM009D-EN-P - April 2004
Communicating with
FLEX I/O Modules
In this chapter, we tell you about:
•
FLEX I/O module data
•
selecting an addressing type
•
selecting an addressing mode
•
determining rack size
•
mapping data into the image tables
•
operating modes
There are 2 types of data associated with FLEX I/O modules: input
data and output data.
•
input data – data read from the module by the processor
•
output data – data written to the module by the processor
Some digital I/O modules have both input and output data associated
with them. Digital I/O modules map input data and output data to the
input and output image tables in the processor. Input and output data
can be defined as:
•
real I/O data – data that represents the actual state of
hardwired inputs and outputs (input data on input modules,
output data on output modules)
•
configuration/status data – data written to configure the
module (such as delay times); and status information (such as
a fuse blown indication)
For FLEX analog modules, input and output data is only accessible
by the processor using block transfer instructions. The data is
contained in block transfer write (BTW) and block transfer read
(BTR) data files, not in the input and output image tables. A byte of
input image and a byte of output image is required for the module
status byte (MSB) and the module control byte (MCB). The MSB
uses input image, and the MCB uses output image. These bytes are
required for block transfer command communications.
Chapter Objectives
FLEX I/O Module Data