Transferring digital frequency signals to same position over task limits

Question:

How can digital frequency signals be transferred over task limits without incremental losses?

Answer:

Many task interrupts by the multitasking system can cause incremental losses if a digital frequency signal (*_v) is to be transferred to the same position from one task to another. Digital frequency signals should only be used in the task in which they were created. For this, eg the DFIN must be called separately in the individual tasks.

If a _v signal must be transferred over a task limit, decide whether the signal can be transferred as speed  value only or if a position reference to the same increment is necessary. In the first case the signal can be transferred directly, in the latter the signal must first be integrated. For the integration, the position range should be limited. The integrated signal is then transferred to the other task as described under 20031727 and reconverted there to the speed signal (*_v) using a differentiator.

In the following diagram the task with the higher priority is represented negative and the task with the lower priority is represented positive. The variable to be transferred is l_InternalAction_v {Task_1, ID=2, T#2ms}. The result of the transfer is available in l_TransmittedVelocity_v {Task_3, ID=4, T#5ms} in the same position. The variable g_IntegrationLength_p synchronises integrator and differentiator.