Tightening Results in Async Data
The following section provides an example of communication between the fieldbus master and controller using Async data when the I/O signals Fieldbus AsyncData to PF and Fieldbus AsyncData from PF are used.
Fieldbus master receives the signal Cycle Complete when a tightening is completed and the tightening result is ready to be fetched on receiving the signal Cycle Complete after a tightening.
Fieldbus master sends the I/O signal 10077 - Fieldbus AsyncData to PF, requesting the first package of result data which is read by the controller.
Controller responds with I/O signal 107 - Fieldbus AsyncData from PF with a sub-package of the tightening result.
The tightening result from the controller may not be bigger than the maximum size of the fieldbus frame.
When the fieldbus master finished reading the first package, the command Fieldbus AsyncData to PF is set to zero indicating that the first sub message has been received and read.
The controller responds with the an acknowledge message Fieldbus AsyncData from PF that a new sub package tightening result can be requested again.
The fieldbus master reads the data frame and if the sequence number is negated, it indicates that the requested sub package is the last in queue.
If the fieldbus master requests the tightening results and the queue is empty, then the controller responds with an empty data frame.
