Emerson SI-DeviceNet User Manual page 8

A fieldbus topology such as DeviceNet allows the same configuration to be realised
using only 2 signal wires plus a shield and power. This method of communication saves
significantly on the amount of cabling required and can improve overall system
reliability, as the number of inter-connections is greatly reduced.
Figure 2-2 shows a typical DeviceNet system transferring the same signals as given in
the traditionally wired example. The signals are now transmitted by converting them into
a serial data stream which is received by the master as if they were connected using
traditional wiring. The data stream on DeviceNet allows up to 56 (28 input and 28
output) independent values to be sent or received by the master, there are also methods
available (non-cyclic data) to allow random access to drive parameters.
Figure 2-2 DeviceNet overview
Table 2.2 Data mappings for SI-DeviceNet
Number of
network words
1
8
DeviceNet master
Digital 1A
Analog 1
Type
digital inputs slave 1 to master
digital outputs master to slave 1
analog output master to slave 1
digital inputs slave 2 to master
digital outputs master to slave 2
analog output master to slave 2
Analog 1 Analog 2
Digital 1B Digital 2A Digital 2B
Analog 2
Source / Destination Description
status signals
control signals
control signal
status signals
control signals
control signal
SI-DeviceNet User Guide
Issue Number: 2