Rockwell Automation 1794-IT8,D17946.5.7 Thermocouple/Millivolt Input Module - Manual (Page 23)

Chapter
3
Publication 1794-6.5.7
Module Programming
In this chapter, we tell you about:
•
block transfer programming
•
sample programs for the PLC-3 and PLC-5 processors
Your thermocouple/mV 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
thermocouple 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 thermocouple/mV module is
not powered up before the remote I/O adapter, the
adapter will not recognize the module. Make certain
that the thermocouple/mV 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 and block transfer read
activity.
Chapter Objectives
Block Transfer
Programming