Special tasks: xBusSync

The task xBusSync was introduced to support special applications for which the standard workflow exposed is not enough.The task is optional and is performed cyclically, if required, synchronous to one of the I / O bus and available to a priority higher than the one of the FAST task. The activation of the task and the combination with the I/O bus is possible from the options menu in expert mode.Due to its characteristics, the task is intended to operate in time periods of less than the FAST task: that’s why the I/O that the task should refer cannot be the standard one because the process image of the PLC 1131 is updated by the FAST task .To manage I/O in the task xBusSync the following dedicated FBs are available:GFB_DIR_IO_GET_HANDLE : to request handles for accessing I/O variables in “direct” modeGFB_DIR_IN_GET_VALUE : to read “directly” an input value by handleGFB_DIR_OUT_SET_VALUE : to write “directly” an output value by handleTo use described FBs you should enable the I/O “direct” management for the chosen buses : it is possible to do that in the same options menu close to xBusSync configuration.A watch dog task control is performed automatically calibrated on the cycle period of the I/O bus that xBusSync task is connected; it’s possible to change the default setup using GFB_SYS 620.