46
• Fieldbus Coupler/Controller
Fieldbus Coupler 750-306
WAGO-I/O-SYSTEM 750
DeviceNet
3.1.4 Process Image
After powering up, the Coupler recognizes all I/O modules plugged into the
node which supply or wait for data (data width/bit width > 0). In the nodes,
analog and digital I/O modules can be mixed.
The Coupler produces an internal process image from the data width and the
type of I/O module as well as the position of the I/O modules in the node. It is
divided into an input and an output data area.
The data of the digital I/O modules is bit orientated, i.e. the data exchange is
made bit for bit. The analog I/O modules are all byte orientated I/O modules,
i.e. modules where the data exchange is made byte for byte. These I/O mod-
ules include, for example, the counter modules, I/O modules for angle and
path measurement as well as the communication modules.
Note
For the number of input and output bits or bytes of the individual I/O mod-
ules, please refer to the corresponding I/O module description.
The data of the I/O modules is separated for the local input and output process
image in the sequence of their position after the Coupler in the individual pro-
cess image.
In the respective I/O area, analog modules are mapped first, then all digital
modules, even if the order of the connected analog and digital modules does
not comply with this order. The digital channels are grouped, each of these
groups having a data width of 1 byte. Should the number of digital I/Os ex-
ceed 8 bits, the Coupler automatically starts another byte.
Note
A process image restructuring may result if a node is changed or extended. In
this case, the process data addresses also change in comparison with earlier
ones. In the event of adding a module, take the process data of all previous
modules into account.
