Title:001_msc.txt participant MTimer participant Master participant M participant S participant STimer participant Sub M->S:GET Note over M,S:M is link level master\ndoing busy poll S->M:GET-NONE Note over Master:TRY Master->MTimer:START[1] Master->M:DO[1] M->S:SET-DO[1] S->M:SET-ACK S->STimer:START[1] S->Sub:DO[1] M->S:GET MTimer->MTimer:TICK[1.1] S->M:GET-NONE Sub->Sub:OK[1] Sub->S:DONE[1] S->STimer:STOP[1] M->S:GET S->M:GET-DONE[1] MTimer->MTimer:TICK[1.2] Note over Master:In time M->Master:DONE[1] Master->MTimer:STOP[1] M->S:GET Note over Master:REPEAT S->M:GET-NONE Master->MTimer:START[2] Master->M:DO[2] M->S:SET-DO[2] S->M:SET-ACK S->STimer:START[2] S->Sub:DO[2] Sub->Sub:NO[2.1] MTimer->MTimer:TICK[2.1] M->S:GET Note over Sub:Busy time sliding S->M:GET-NONE STimer->STimer:TICK[2.1] STimer->S:TOCK[2.1] Sub->Sub:NO[2.2] M->S:GET Note over S:? MTimer->MTimer:TICK[2.2] S->M:GET-NONE Sub->Sub:OK[2] Sub->S:DONE[2] S->STimer:STOP[2] M->S:GET S->M:GET-DONE[2] MTimer->MTimer:TICK[2.3] MTimer->Master:TIMEOUT[2] Note over Master:Too late\nToo bad\nCoding error M->Master:DONE[2] Note over Master:Didn’t help\nWill not proceed