General limitations
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The PLC simulator simulates a complete project with its user tasks. However, the runtime behavior of the simulator cannot be compared to that of a real PLC and cannot be used to draw conclusions about the behavior of a real PLC. This includes Multitasking behavior and time information.
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The PLC Simulator does not support any form of I/O. Although the simulation contains project components for I/Os, they are not processed by the PLC simulator. Inputs and outputs can only be accessed via the project or via the Control Expert online functions (read, write, force, animate, ...).
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With the PLC simulator I/O events can not be triggered by setting/forcing %I bits.
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The PLC Simulator does not support any Hot Standby feature.
The PLC simulator supports the most PLC OS system services on a variety of platforms. These services are only implemented as dummy services.
This means that functions and function blocks can be used in the loaded project, but they do not work as expected and/or they return an error message.
This mainly affects functions and function blocks that accessed special platforms, such as I/O blocks, communication and hardware specific functions.
The following PLC OS system services are supported:
The following PLC OS system services are not supported:
The different PLC families vary in memory structure.
NOTE: PLC Simulator is a 16 bits application, whatever PLC in application is (Quantum, Premium, M580...). This is why you must rebuild your application when you switch from real PLC to Simulator.
Communication limitations
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The PLC simulator only supports TCP/IP based communication (Schneider Port 502). In other cases a Modbus exception code is returned.
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Modbus, Modbus Plus or Uni-TE are not supported by the PLC simulator.
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For Control Expert V14.1 and earlier the PLC simulator does not support communication to other PCs or PLC simulators, neither remote nor local.
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For Control Expert V14.1 and earlier, the PLC simulator has no communication timeout.
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Communication network, such as Uni-Telway, Ethway, Fipway, Modbus, Modbus Plus, etc., are not supported by the PLC simulator.
The PLC simulator supports the following native Modbus commands:
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Function Code (in hex)
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Description
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01
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Read Coil Status (0x)
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02
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Read Input Status (1x)
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03
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Read Holding Registers (4x)
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04
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Read Input Registers (3x)
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05
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Force Single Coil (0x)
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06
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Preset Single Register (4x)
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0F
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Force Multiple Coils (0x)
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10
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Preset Multiple Registers (4x)
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16
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Mask Write Registers (4x)
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Mapping a
%MW to a Boolean Element
Regarding the use of %MW mapped on a boolean element in structured data type, the PLC simulator and a real PLC behave different.
When a %MW is mapped on a boolean element in structured data type, only the first row is animated by the PLC simulator. On a real PLC both rows (zero and one) are animated. Row one is used to get the information about the history value.
Control Expert XLS Safety Project Limitations
The following limitations apply to the PLC simulator working with safety projects built with Control Expert XLS:
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The PLC simulator has no double code execution of the logic and comparison of the results. It only simulates the logic but not the safety behavior of the PLC.
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It is not possible to transfer a non-safety project after you have transferred a safety project to the PLC simulator and vice versa.
The PLC simulator could enter HALT state when executing the Step Info or Step Over debugging command in textual languages.
If the current element is a complex instruction (i.e. copying a huge array from one variable to another), the execution of this instruction takes a very long time, because it will be executed in single step mode on the PLC simulator.
Setting a breakpoint on the next instruction and executing the Go command avoids this problem.
In case of division by 0 the %SW125 is set to:
WARNING 