Since HDLC is used a lot in master-slave scenarios the P/F, or Poll/Final, bit is used to co-ordinate communication
Since HDLC is used a lot in master-slave scenarios the P/F, or Poll/Final, bit is used to co-ordinate communication
The master initiates the conversation by sending a P to the slave
The slave is then allowed to sending a number of frames back to the master, each one also with the P/F bit set to P. When the slave send the last frame it sets the bit to F to inform the master that it is finished
It can also be used to force an instant acknowledgement