Chapter
3
Publication
17946.5.2 - May 1996
Module Programming
In this chapter, we tell you about:
• analog data format
• block transfer programming
• sample programs for the PLC-3 and PLC-5 processors
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 scaling, alarms, 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.
!
ATTENTION: If the analog module is not powered
up before the remote I/O adapter, the adapter will not
recognize the module. Make certain that the analog
module is installed and powered before or
simultaneously with the remote I/O adapter. If the
adapter does not establish communication with the
module, cycle power to the adapter.
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.
Chapter Objectives
Block Transfer
Programming
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