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.
When a PLC or SLC runs a ladder logic program, the following occurs:
- The inputs from your physical I/O generate a response in your processor’s data table.
- 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).
- 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.
There are several instructions that RSLogix Emulate will not emulate. These are listed in the table below:
|
Mnemonic
|
Instruction |
Execution |
|
BTR |
Block Transfer Read |
There is no real I/O to read. The software will not emulate the actual transfer of data, but the enable (.EN) and done (.DN) bits are emulated. |
|
BTW |
Block Transfer Write |
There is no real I/O to read. The software will not emulate the actual transfer of data, but the enable (.EN) and done (.DN) bits are emulated. |
|
COR |
Custom Output Routine |
The COR instruction passes parameters to a Custom Application Routine (CAR) file. CAR files are not emulated in any way. The instruction is not executed. |
|
CPW |
Copy Word |
(SLC 500 only) This instruction is not executed. |
|
DLG |
Data Log |
(MicroLogix 1500 only) The data logging function is not emulated. The instruction is not executed. |
|
GCD |
Gray Code |
(SLC 500 only) This instruction is not executed. |
|
HSC |
High Speed Counter |
(SLC 500 only) This instruction is not executed. |
|
IDI |
Immediate Data Input |
There is no I/O image table to update in the software. This instruction is not executed. |
|
IDO |
Immediate Data Output |
There is no I/O image table to update in the software. This instruction is not executed. |
|
IID |
I/O Interrupt Disable |
(SLC 500 only) There is no I/O to generate an interrupt, therefore this instruction has no effect. |
|
IIE |
I/O Interrupt Enable |
(SLC 500 only) There is no I/O to generate an interrupt, therefore this instruction has no effect. |
|
IIM |
Immediate Input with Mask |
(SLC 500 only) There is no I/O to update, therefore this instruction has no effect. |
|
IIN |
Immediate Input |
There is no I/O image table to update in the software. The instruction is not executed. |
|
INT |
Specialty I/O Interrupt |
(SLC 500 only) There is no I/O to trigger an interrupt, therefore this instruction has no effect. |
|
IOM |
Immediate Output with Mask |
(SLC 500 only) There is no I/O to update, therefore this instruction has no effect. |
|
IOT |
Immediate Output |
There is no I/O image table to update in the software. The instruction is not executed. |
|
MSG |
Message |
Even though the software provides Data Highway Plus emulation and Channel 0 emulation, the MSG instruction emulates only the enable (.EN) and disable (.DN) bits. |
|
PID |
Proportional, Integral, Derivative |
The software does not attempt to execute the PID instruction or change any of the PID control bits or words. |
|
PTO |
Pulse Train Output |
(MicroLogix 1200 and 1500 only) There are no outputs. The instruction is not executed. |
|
PWM |
Pulse Width Modulation |
(MicroLogix 1200 and 1500 only) There are no outputs. The instruction is not executed. |
|
RCP |
Recipe |
(MicroLogix 1500 Series C only) This instruction is not executed. |
|
REF |
I/O Refresh |
(SLC 500 only) There is no I/O to refresh, therefore this instruction has no effect. |
|
RPI |
Reset Pending I/O Interrupt |
(SLC 500 only) This instruction is not executed. |
|
RPI |
Reset Pending I/O Interrupt |
(SLC 500 only) There is no I/O to generate an interrupt, therefore this instruction has no effect. |
|
RTA |
Real Time Clock Adjust |
(MicroLogix 1200 and 1500 Series C) This instruction is not executed. |
|
SVC |
Service Communications |
(SLC 500, MicroLogix 1200 and 1500) There are no processor communications to service, therefore this instruction has no effect. |