Rockwell Automation 1761-NET-DNI DeviceNet Interface (DNI) - Manual (Page 19)

Publication 1761-UM005B-EN-P - October 2006
Operation 19
Messaging Services The capabilities of each individual device determine what level of
messaging is supported. The types of messaging supported are:
• I/O Assembly Messaging (DNI responds)
• PCCC encapsulated DeviceNet Messaging (peer-to-peer)
• Explicit Assembly Messaging (DNI initiates, DNI Series B Only)
See Explicit Messaging (DNI Series B Only) on page 77 for more
information.
I/O Assembly Messaging
Two conditions must be met to access the I/O assemblies.
• Data Enable (DNI Series A) or I/O Scan Enable (DNI Series B)
must be enabled.
• The DF1 Device must be servicing the Heartbeat.
See DF1 Heartbeat on page 43 for information on using the
Heartbeat.
The following sections describe additional conditions based on the
DNI Series.
DNI Series A
DNI Series A supports explicit messaging to the master I/O assemblies
over DeviceNet at a minimal level. If the DNI is not owned by a
DeviceNet master, the DNI responds to explicit messaging gets and
accepts explicit messaging sets to the master I/O assembly. If the DNI
is owned by a DeviceNet master, it responds to gets, but cannot
accept sets. In either case, the data size must be 16 words, even if the
I/O size is smaller.
See page 65 to address DNI Series A assemblies.
DNI Series B
DNI Series B provides the above described functionality, except the
data size is equal to the configured I/O size. Additionally, DNI Series
B can respond to explicit messages over DeviceNet to its explicit I/O
assemblies whether it is owned by a DeviceNet master or not.
See page 66 to address DNI Series B assemblies.
DNI Series B can also perform get/set services with its new DeviceNet
messaging capability.
See page 77 for Explicit Messaging (DNI Series B Only).