In this section you will find some tips for drawing and simulating systems.
In PLC-Lab it is possible to specify operands with absolute addresses in the properties for operands within the objects as well as the symbols of operands which were previously defined in the symbol table.
We recommend that you enter an operand in the symbol table and assign a symbol there before using it in an object property.
This offers several advantages:
The following link describes how to enter symbols into the properties of objects with as little typing as possible: Using symbols in objects
If a new system is developed and it is a slightly more complex system, then input operands of the Sim device should first be used for the actions in the system and not, for example, output operands of a PLC, which can only be switched over via the PLC program. The input operands of the Sim-Device can be influenced directly via e.g. switch or push-button objects and thus the reaction of the virtual system can be tested directly without a PLC program (or Grafcet).
If the behaviour of the virtual system is as intended, the Sim input operands can be replaced by the respective device operands (PLC or Grafcet). Then the actuators of the system can also be changed to the output operands by changing the input operand in the symbol table to an output operand.
If you only want to process data within the PLC Lab system, use the flag operands of the IM device.
We recommend the following approach:
If a limit switch is placed in a system, it is a proven method to also specify the limit switch operand in the property "Operand switching fill color".
In this way, the status of the limit switch operand can be recognized immediately during simulation.
When using cylinders and their limit switches, you should additionally place two lamp objects where the limit switch operands are specified. During the simulation, you can immediately see whether the cylinder is in a particular end position and whether the associated limit switch is activated.
If you have used analog sensors or default values in a system, e.g. the position data of a prismatic joint or the spin velocity for rotations, it is usually helpful to display the numerical values of the digital operands in a label.
You can find out how to do this by clicking on the following link. Displaying the value of an operand in a label