What RSLogix Emulate does

RSLogix Emulate is a troubleshooting and debugging tool that can emulate most operations of Allen-Bradley PLC-5 and SLC 500 family processors. It executes your ladder logic programs in your computer, updating your programs' data tables, allowing you to approximate what is going to happen when you download your programs to physical PLC-5 processors.

Caution: While RSLogix Emulate is useful for verifying the integrity of your program, you should not rely solely on the software for final program checkout. Variations in processor function (and variations based on processor series and revision) dictate that final checkout must be performed with the actual processor and I/O for your system.

When a PLC or SLC runs a ladder logic program, the following occurs:

1. The inputs from your physical I/O generate a response in your processor's data table.
2. The processor executes your ladder logic, using the inputs from your I/O and other data table values to generate new values for your outputs (and other data table values).
3. The output values in your data table are applied to your outputs in physical I/O.

This sequence of events is called one program scan. Depending on the processor and the program, 10 to 50 program scans occur each second.

When you use Rockwell Software products to program your processor, the ladder logic and data table are stored in your computer. RSLogix Emulate executes the stored ladder logic and updates the data table as if the processor was running.

There's something missing when RSLogix Emulate runs a processor's program: the I/O. Since your computer will not be connected to your I/O modules, the software uses debug files to simulate the inputs for your ladder logic program.

Debug files are sections of ladder logic that you program to simulate your process' inputs. The ladder logic in a debug file can be edited like any other program file.

RSLogix Emulate has some powerful troubleshooting features. You can:

• scan your ladder logic continuously, one rung at a time, or one program scan at a time
• restrict the program scan to a block of rungs that you specify
• set breakpoints in your ladder logic to stop execution when a specified event occurs (e.g., when an important value goes out of range), freezing the conditions that caused the breakpoint to trigger

The software also allows you to emulate Channel 0 on your processor (for those projects that use New Platform PLC-5s or the SLC-5/03 and -5/04). This feature is handy for troubleshooting programs that interface with serial devices (e.g., bar code readers, scales, terminals, etc.).

As a debugging tool, you can feed trend data into the software to "replay" your data through your ladder logic.