Rockwell Automation 20-COMM-Q ControlNet Adapter - Manual (Page 130)

6-2 Using Explicit Messaging
20-COMM-C/Q ControlNet Adapter User Manual
Publication 20COMM-UM003F-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 ControlNet
Object Class code compatibilities for these drives.
Table 6.A Explicit Messaging Class Code Compatibility with Drives
ControlNet 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), and Host parameters
(Ports 7…14 only). For example, DPI Parameter Object Class code 0x93 can access a 20-COMM-C 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
DPI Parameter Object on page C-16 for instance (parameter) numbering.
Single and scattered parameter
reads/writes
Host DPI Parameter
Object 0x9F No Yes
(2)
with limitations
(2) Enables access to drive parameters (Port 0) and Host parameters for all ports (1…14). Host DPI Parameter
Object Class code 0x9F cannot access DPI (device) parameters. For example, if a 20-750-DNET option module
is in Port 4, its Host parameters can be accessed, but not its DPI (device) parameters. See
Host DPI Parameter
Object on page C-30 for instance (parameter) numbering.
Single and scattered parameter
reads/writes