I used asynchronous task specification block in a subsystem and that subsystem's input port 1 is driven by function generator(generated by stateflow chart). i am getting compilation error as "The function call input port 1 of model block 'Variant_Logic/Variant Model/Model1' must be driven by an asynchronous function call initiator."
The reason that you are getting the above error is because the Asynchronous task specificationblock is NOT triggered by Asynchronous interrupt. The Inport block for Asynchronous task specification block must receive an interrupt signal from an Async Interrupt block that is in the parent model.
For more information refer to the below documentation link