I/O
Modules • 105
WAGO-I/O-SYSTEM 750
DeviceNet
5.2 Process Data Architecture for DeviceNet
With some I/O modules, the structure of the process data is fieldbus specific.
In the case of a DeviceNet coupler/controller, the process image uses a byte
structure (without word alignment). The internal mapping method for data
greater than one byte conforms to the Intel format.
The following section describes the process image for various
WAGO-I/O-SYSTEM 750 and 753 I/O modules when using a DeviceNet cou-
pler/controller.
Note
Depending on the specific position of an I/O module in the fieldbus node,
the process data of all previous byte or bit-oriented modules must be
taken into account to determine its location in the process data map.
For the PFC process image of the programmable fieldbus controller is the
structure of the process data mapping identical.
5.2.1 Digital Input Modules
Digital input modules supply one bit of data per channel to specify the signal
state for the corresponding channel. These bits are mapped into the Input
Process Image.
When analog input modules are also present in the node, the digital data is al-
ways appended after the analog data in the Input Process Image, grouped into
bytes.
Some digital modules have an additional diagnostic bit per channel in the In-
put Process Image. The diagnostic bit is used for detecting faults that occur
(e.g., wire breaks and/or short circuits).
Each input channel seizes one Instance in the Discrete Input Point Object
(Class 0x65).
1 Channel Digital Input Module with Diagnostics
750-435
Input Process Image
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Diagnostic
bit
S 1
Data bit
DI 1
The input modules seize 2 Instances in Class (0x65).
