9/12/2023 0 Comments Rslogix using tag as timer presetWhen creating a Safety controller project, the Logix Designer programming application creates the SafetyTask, with a Safety program and a main Safety routine. When creating a new project, the MainTask is already defined as a continuous task. There are 15 configurable priority levels for periodic and event tasks ranging from priority 1 (the highest priority) to 15 (the lowest priority). In ControlLogix and CompactLogix PLCs, up to 32 tasks can be created, of which one can be a continuous task if desired. If the controller detects a periodic task trigger for a task already operating, a minor PLC fault occurs. If you’re working with multiple periodic tasks, ensuring sufficient time for the CPU to handle the task interruption is essential. Regardless of which task type is best for your application, the most important thing to remember is to ensure that the selected time period does not exceed the sum of all the execution times of ALL programs assigned to a particular task. The RPI of the consumed tag determines the period at which the data updates.Įvent Task Trigger Options Creating Tasks and Setting Times in RSLogix 5000 The data type of the consumed tag must match the data type (including any array dimensions) of the produced tag. A produced tag sends its data to one or more consumed tags (consumers) without using logic.Ī Consumed tag is a tag that receives the data of a produced tag. Multiple controllers can simultaneously consume (receive) the data. Once again, like the periodic task, it will be executed only once, at which point the previous task will continue from where it left off.īefore trying to use specific triggers, it's best to check whether they are supported by the controller you will be using, as some Logix 5000 controllers do not support all triggers.Īn event-driven task can be triggered by many things, for example Ī Produced tag is a tag that a controller makes available for use by other controllers. As soon as a trigger is received, the event task will be executed immediately, interrupting any lower-priority tasks. Periodic Task Property Window Understanding Event Tasks in RSLogix 5000Īn event task will perform a function when a specific event or trigger occurs, meaning it is not continuously operating. Although a continuous task is not required to process program logic, there can only be one configured. As soon as it completes executing all the code in the PLC, it restarts immediately from the beginning. In the continuous task, all logic within a PLC is executed in order, rung by rung. Therefore, any CPU time not allocated to other operations, such as motion or communication, will be used to process the programs within the continuous task. A project will, by default, contain a continuous task running in the background. In RSLogix 5000, logic is executed based on tasks and events. Understanding Continuous Tasks in RSLogix 5000 Which type of task would be best suited to our indexing table example? That’s what we’re going to look at in this tutorial. One way to overcome this issue is using a different task type. This could be detrimental to our machine. This would mean that our indexing table might stop short or overshoot our dwell flag. For example, one scan to the next could be longer or shorter than the last. Imagine using the main PLC task with various processes and calculations. At the falling edge of the dwell flag, a timer could be started, and once the timer has expired, a virtual stop command can be sent to the PLC to stop and decelerate the table, allowing it to come to rest on the dwell flag. Another way to achieve the same result is to start indexing the table. When the table rotates to this flag, it will command the PLC to stop and decelerate the table allowing it to come to rest on the dwell flag again. At a certain point, fixed to the spindle of the indexer sits a stop flag. As the indexing table rotates, it moves off of the dwell flag. For example, a traditional setup might include both flags as inputs to the PLC. Given the advancements of PLCs these days with multicore processors, we can improve our scan times and, therefore, process information much more quickly.Īn example of this might be accurately timing a process such as an indexing table with a dwell flag but no stop flag. When writing code for fast automation processes, such as in the FMCG (Fast Moving Consumer Goods) sector, the processing speed of PLC logic can sometimes have significant implications.
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