About explicit messaging, About explicit messaging -2 – Rockwell Automation 20-COMM-D DeviceNet Adapter Series B FRN 2.xxx User Manual
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Using Explicit Messaging
20-COMM-D DeviceNet Adapter User Manual
Publication 20COMM-UM002G-EN-P
About Explicit Messaging
Explicit Messaging is used to transfer data that does not require continuous
updates. With Explicit Messaging, you can configure and monitor a slave
device’s parameters on the network.
Important: When an explicit message is performed, by default no
connection is made because it is an ‘unconnected’ message.
When timing of the message transaction is important, you can
create a dedicated message connection between the controller
and drive by checking the ‘Connected’ box on the
Communications tab message configuration screen during
message setup. These message connections are in addition to
the I/O connection. However, the trade off for more message
connections is decreased network performance. If your
application cannot tolerate this, we recommend to not check the
‘Connected’ box.
Important: PowerFlex 7-Class and PowerFlex 750-Series drives have
explicit messaging limitations.
Table 6.A
shows the DeviceNet
Object Class code compatibilities for these drives.
Table 6.A Explicit Messaging Class Code Compatibility with Drives
DeviceNet Object
Class Code
PowerFlex
7-Class Drives
PowerFlex
750-Series Drives Explicit Messaging Function
Parameter Object
0x0F
Yes
No
Single parameter reads/writes
DPI Parameter
Object 0x93
Yes
Yes
(1)
with limitations
(1)
Enables access to drive parameters (Port 0), DPI device parameters (Ports 1…6 only). For example, DPI
Parameter Object Class code 0x93 can access a 20-COMM-D adapter in Port 6. However, Class code 0x93
cannot access, for example, the Host parameters in a 24V I/O option module in Port 5. See
for instance (parameter) numbering.
Single and scattered parameter
reads/writes
Host DPI Parameter
Object 0x9F
No
No
Single and scattered parameter
reads/writes