Balluff BIS M-370-000-A02, Manual, Page: 130 / 198

PROFIBUS INTERFACE
123
9
Figure 68 - Exchange Area Buffer Structure
9.4.2 Control Field
The Input field structure reserves IN[0] for handshake purposes: bit 0 and bit 1 are used for
this. Bit 6 is set to 1 in order to specify the messaging protocol number 1 is in use. The
Output field structure is symmetrical, and reserves bit 0 and 1 for handshake purposes. Bit 6
is set to 1 in order to specify the messaging protocol number 1 is in use. Bit 2 of the Output
buffer is used to request a clear of the synchronization numbers (bit 0 and bit 1 of both Input
and Output buffers).
This is called a resynchronization request and it is always initiated by the Master Station. The
Slave must acknowledge the request, using bit 2 of the Input buffer. Bit 3 is used to control a
fragmentation sequence in both directions.
More precisely,
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 = RxBufferEmpty, toggles when rx block has been read on OUT[1] .. OUT[
Nout]
IN[0].bit2 = Resync Acknowledge, set to 1 as an acknowledge to a resync request.
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].bit4,5,7 = set to 0,0,0 when this messaging protocol is used.
IN[0].bit6 = set to 1 when this messaging protocol is used.