Rockwell Automation 1794-IF4I, -OF4I, IF2XOF2I, -IF4IXT, -IF4ICFXT, -OF4IXT, IF2XOF2IXT FLEX I/O Isolated Analog Modules - Manual (Page 31)

31 Publication 1794-6.5.8 - January 2010
Chapter
1
Module Programming
Chapter Objectives In this chapter, we tell you about:
•
analog data format
•
block transfer programming
•
configuration rungs
•
sample programs for the PLC-3 and PLC-5 processors
Block Transfer
Programming Your module communicates with the processor through bidirectional
block transfers. This is the sequential operation of both read and write
block transfer instructions.
A configuration block transfer write (BTW) is initiated when the
analog module is first powered up, and subsequently only when the
programmer wants to enable or disable features of the module. The
configuration BTW sets the bits which enable the programmable
features of the module, such as filters and signal ranges, etc. Block
transfer reads are performed to retrieve information from the module.
Block transfer read (BTR) programming moves status and data from
the module to the processor’s data table. The processor user program
initiates the request to transfer data from the module to the processor.
The transferred words contain module status, channel status and input
data from the module.
The following sample programs are minimum programs; all rungs and
conditioning must be included in your application program. You can
disable BTRs, or add interlocks to prevent writes if desired. Do not
eliminate any storage bits or interlocks included in the sample
programs. If interlocks are removed, the program may not work
properly.
Your program should monitor status bits, block transfer read and
block transfer write activity.