Rockwell Automation 57C415 24V AC/DC Input Module - Manual (Page 15)

4Ć1
4.0 PROGRAMMING
This section describes how data is organized in the module and
provides examples of how the module is accessed by the application
software. For more detailed information, refer to the AutoMax
Enhanced BASIC Language Instruction Manual (JĆ3675).
4.1 Register Organization
The data in the module is organized as one 16 bit register. The
software allows you to define the module as a single register (up to
16 bits) by referencing the entire module as a unit, or as up to 16
individual bits by treating each of the bits separately. Refer to figure
4.1.
register 0 R R R R R R R R R R R R R R R R
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Figure 4.1Ć Organization of Register Bits
4.2 Configuration
Before any application programs can be written, it is necessary to
configure, or set, the definitions of systemĆwide variables, i.e. those
that must be globally accessible to all tasks.
For DCS 5000 and AutoMax Version 2.1 and earlier, you define
systemĆwide variables by writing a Configuration task. For AutoMax
Version 3.0 and later, you define systemĆwide variables using the
AutoMax Programming Executive. After these variables are defined,
you can generate the configuration file automatically, which
eliminates the requirement to write a configuration task for the rack. If
you are using AutoMax Version 2.1 or earlier, refer to Appendix E for
examples that show how to define variables in the configuration task.
If you are using AutoMax Version 3.0 or later, see the AutoMax
Programming Executive (JĆ3750) for information about configuring
variables.
4.3 Reading Data In Application Tasks
In order for an input module to be referenced by application
software, it is necessary to assign symbolic names to the physical
hardware. This is accomplished by either IODEF or RIODEF
statements in the configuration task.
Each application program that references the symbolic names
assigned to the input module in configuration must declare those
names COMMON.
The frequency with which tasks read their inputs and write their
outputs depends on the language being used. Ladder logic and
control block tasks read inputs once at the beginning of each scan
and write outputs once at the end of scan. BASIC tasks read an input
and write an output for each reference throughout the scan.