Rockwell Automation 1771-N SERIES High Resolution Analog Module User Manual - Manual (Page 34)

3–2 Communicating With Your Analog Module
Publication 1771ĆUM127B-EN-P - December 2002
Your analog module works with a default configuration upon
powerup as long as a block transfer write (BTW) has not been
initiated. See the configuration default section in chapter 4 to
understand what this configuration looks like. Refer to the sample
programs in this chapter 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 the 1771-N series module to powerup and
operate.
Due to the number of digits required for high resolution readings, the
1771-N series modules normally read input values in 2’s complement
binary. Binary coded decimal (BCD) can be used, but with lower
resolution. As a result, the 1771-N series modules are not
recommended for use with PLC-2 family programmable controllers.
Block transfer instructions with the PLC-3 processor use three data
table files. A binary file is used for module location and other related
data. This is the block transfer control file. Two separate block
transfer data files store data that you want transferred to the module
(when programming a block transfer write) or from the module
(when programming a block transfer read). The address of the block
transfer data files are stored in the block transfer control file.
The industrial terminal prompts you to create a control file when a
block transfer instruction is being programmed.
The same block
transfer control file is used for both the read and write
instructions for your module. A different block transfer control file
is required for every module.
An example program segment with block transfer instructions is
shown in Figure 3.1, and described below.
PLCĆ2 Programming
PLCĆ3 Program Example