Specifications

C - 8 RSLinx – Training Guide
“Simulating” real world conditions
Since the Emulator functions from within the computer environment, there needs to be
some way of making the ladder program "think" that there is some real world I/O
connected. The emulator allows for a variety of means of creating “action” in the emulated
PLC, as well as offering several special troubleshooting tools you wouldn’t have with a
real PLC.
Data Table
First of all, the emulated ladder logic program’s data table will act exactly as a real PLCs
data table. So one option for simulating I/O and causing rung conditions to change is to
write to the data table. This can be done using any means that one might normally use to
write to the data table. For example, from LINX, one can write to the data table via the
PLC Monitor option. Or from RSLogix 5, again, one could write data to the data table via
all the normal means - one can simply write values to the data table, turn bits on or off,
etc..
Or from an HMI such as RSView32 or WINtelligent VIEW, one has countless means of
writing to the data table, for example, having some sort of download function from an
operator interface screen. In other words, from an operator interface screen which would
normally download a value to a PLC to change a timer preset, one could change the timer
preset in the emulated PLC, and the ladder logic and data table would react accordingly.
Trouble shooting and “Debug” Tools
The actual writing of a ladder logic program is often only a small portion of the complete
development cycle. The checkout and troubleshooting of a new program can involve
considerably more time (and expense) than did the planning for and entry of the program.
The Rockwell Software Emulator was developed as a way to "work out the kinks" early in
the program development cycle. Trapping program errors can be difficult at best. Often as
the errors occur, data table values and the state of inputs or outputs change. In the process
they invariably erase any of the clues that you would normally use to track down the
problem.
Built into the Emulator are powerful "tools" to help isolate problems. These tools are
discussed later in this guide.