Rockwell Automation 1771-IR , D17716.5.76 RTD INPUT MODULE - Manual (Page 18)

Chapter
4Ć1
Module Programming
In this chapter, we describe
Block Transfer programming
Sample programs in the PLC–2, PLC–3 and PLC–5 processors
Module scan time issues
Your module communicates with the processor through bidirectional block
transfers. This is the sequential operation of both read and write block transfer
instructions.
The block transfer write (BTW) instruction is initiated when the analog module
is first powered up, and subsequently only when the programmer wants to write
a new configuration to the module. At all other times the module is basically in
a repetitive block transfer read (BTR) mode.
The following example programs accomplish this handshaking routine. These
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 analog input module will work with a default configuration of all zeroes
entered in the configuration block. See the configuration default section to
understand what this configuration looks like. Also, refer to Appendix B for
example configuration blocks and instruction addresses to get started.
Your program should monitor status bits (such as overrange, underrange) and
block transfer read (BTR) activity.
The following example programs illustrate the minimum programming required
for communication to take place.
Chapter Objectives
Block Transfer Programming