Ad-Hoc Communication" Mode - WAGO I/O-SYSTEM 750 Manual

50 Process Image
The maximum value of the cut-off is the total size of the process image minus 2.
If just two 750-644 I/O modules are exchanging data with each other, this maxi-
mum value can be used. In this case, the maximum bandwidth is solely available
to the connection.
However, if a 750-644 I/O module configured as the master exchanges data with
more than one other 750-644 I/O module, the available bandwidth must be
divided between the segments and thus between the slots and configured
Bluetooth
Data is exchanged cyclically, i.e. with low latency and cycle time, but no flow
control. The cycle time, i.e. the time interval to the next transmission of data in
the segment of the PIO, depends on the current configuration. Whether the data
has changed since the previous transmission cycle plays no role. In the PII,
segment data always remains current until updated by a new wireless transmission
from the other 750-644 I/O module.
Example configurations for segments in the process image from master and
slaves:
• "1:1" – Master with 48-byte process image, a cut-off of 0 bytes is set for
slot address 0x20, a cut-off of 46 bytes is set for slot address 0x21. Slave
with 48-byte process image, the cut-off setting is not evaluated. All 46 bytes
are available for data transmission between the master and the slave linked
to slot address 0x21.
• "1:2" – Master with 48-byte process image, 23 bytes for slot addresses 0x20
and 0x22, 0 bytes for all other slot addresses. The slave linked to 0x20 has a
process image of 24 bytes, the slave linked to 0x22 has a process image of
48 bytes. 22 bytes can be exchanged cyclically between master and first-
mentioned slave – the process image of the slave is limiting here. 23 bytes
can be exchanged cyclically between master and second-mentioned slave –
the cut-off set on the master is limiting here.
• "1:7" – Master with 48-byte process image, cut-offs 6, 6, 6, 6, 6, 8, 8 are set
for slot addresses 0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26. In this case,
the limiting factor is always the cut-off set on the master independent of the
size of the process image of the slave.
6.2.2

"Ad-hoc Communication" Mode

In "Ad-hoc Communication" mode, a 750-644 I/O module transmits the process
data of each of its segments of the output process image (PIO) via the RFCOMM
protocol to another assigned Bluetooth
then maps the data received to the associated segment of its input process image
(PII).
Data is exchanged serially, the first byte of each segment is used to control data
flow to and from the 750-644 I/O module and other bytes of the segment contain
serial data. To allow data to be exchanged with the Bluetooth
configured for the respective slot, the cut-off for this segment must be set to at
®
SPP devices.
750-644 Bluetooth
®
SPP device. The 750-644 I/O module
Version 2.0.0, valid from FW/HW Version 03/03
WAGO-I/O-SYSTEM 750
®
RF-Transceiver
®
SPP device
Manual