Rockwell Automation 1771-IXHR , D17716.5.80 HIGH RESOL.THERMOCOUPLE - Manual (Page 19)

Chapter
4Ć1
Module Programming
In this chapter, we describe
Block Transfer programming
Sample programs in the 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. Refer to chapter 5 to see the 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,
alarms, etc.) and block transfer read activity.
The following example programs illustrate the minimum programming required
for communication to take place.
Due to the number of digits required for high resolution readings, the
1771–IXHR module only reads input values in 2’s complement binary. Since
the PLC–2 family PLCs do not naturally read this data format, the IXHR
module is not recommended for use with PLC–2 family programmable
controllers.
Chapter Objectives
Block Transfer Programming
PLC-2 Applications