Instruction manual

Connection box C-BOX 300
The C-BOX PROFIBUS protocol implementation
S
ubject to reasonable modifications due to technical advances. Copyright Pepperl+Fuchs, Printed in Germany
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epperl+Fuchs Group • Tel.: Germany (06 21) 7 76-0 • USA (330) 4 25 35 55 • Singapore 7 79 90 91 • Internet http://www.pepperl-fuchs.com
Date od issue 07/25/2003
26
More precisely:
Figure 5.3 shows how it is possible to exchange messages with flow control using bit
0 and bit 1 in the IN/OUT buffers.
Function of the IN[0] byte:
IN[0].bit0 = TxBufferFull, toggles when new data is available on IN[1] ..
IN[Nin] input area
IN[0].bit1 = RxBuff erEmpt y, toggles when rx block has been read on
OUT[1] .. OUT[ Nout]
IN[0].bit2 = Resync Acknowledge, set to 1 as an acknowl edge to a resync
request . With this bit, the master can det ect a slave is on line.
IN[0].bit3 = More Bit, it must be set to 1 when this is not the last piece of a
fragmentation sequence. It must be set to 0 when this is the last
piece of a fragmentation sequence.
IN[0].bit4,5 = set to 0,0 when this messaging protocol is used.
IN[0].bit6,7 = set to 0,0 when this messaging protocol is used (they corres-
pond to the driver version).
Function of the OUT[0] byte:
OUT[0] .bit0 = TxBufferEmpty, toggles when transmitt ed data block has been
read from master.
OUT[0] .bit1 = RxBufferFull, toggles when new data block is available from
master.
OUT[0] .bit2 = Resync Request, set to 1 for 1 second to resynchronize a slave.
After resynchroni zation, all 4 handshake bits are set to 0 and
next toggle brings them to 1.
OUT[0].bit3 = More Bit, it must be set to 1 when this is not the last piece of a
fragmentation sequence. It must be set to 0 when this is the last
piece of a fragmentation sequence.
OUT[0] .bit4,5 = set to 0,0 when this messaging protocol is used.
OUT[0] .bit6,7 = set to 0,0 when this messaging protocol is used (they corres-
pond to the driver version).