Controllogix 5000 programming manual pdf
To eliminate the chances of this happening, a different type of task may be created to host the program where all the routines implementing PID instructions are assigned to be executed. This, in turn, affects the frequency of output changes that is sent to the final control element and thus the control loop may not react as to how it was initially configured. When the speed at which a continuous task is scanned changes, the frequency of how often the calculations inside the PID instruction is executed also changes. The ‘tuning’ of parameters for a PID loop is in fact the changing of variables for different calculations. This will have an adverse effect on PID loops. The speed at which this occurs may gradually decrease over time, as the project expands or may even drastically increase when the controller is upgraded to a faster controller. Once the task has finished executing, the whole process will be repeated. It will sequentially scan through all the assigned programs, as scheduled by the programmer. A continuous task is one that runs continually. This indicates that ‘MainTask’ is a continuous task. In the folder, a circular arrow can be seen. ‘MainTask’ is automatically created, hosting the ‘MainProgram’. When a new project is created in RSLogix 5000, the following basic configuration under the tasks folder is created automatically. This is a topic that needs brief attention before the actual programming occurs.
When the tank level decreases below the desired level, he will increase the inflow by opening the valve and when the tank level increases to more than the desired level, he will close the valve. The means he has to his disposal to carry out this task is by opening and closing this valve. The instruction was given to him to maintain a desired water level in the tank. An operator visually monitors the level in the tank. This is an example of Manual Level control.