Rockwell Automation 20-750-CNETC PowerFlex Coaxial ControlNet Option Module - Manual (Page 74)

74 Rockwell Automation Publication 750COM-UM003B-EN-P - November 2012
Chapter 6 Using Explicit Messaging
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.
Table 4 - Explicit Messaging Class Code Compatibility with PowerFlex 750-Series Drive
IMPORTANT When an explicit message is performed, by default no connection is made since 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, do not check the ‘Connected’ box, which is recommended.
TIP To message to another device in a different drive port, see the Instance table in
Appendix C:
• DPI Parameter Object section on page 115 for Device parameters.
• Host DPI Parameter Object section on page 129 for Host parameters.
In the Message Configuration dialog box, set the Instance field to an
appropriate value within the range listed for the port in which the device
resides.
IMPORTANT PowerFlex 750-Series drives have explicit messaging limitations. Table 4 shows
the ControlNet Object Class code compatibilities for these drives.
ControlNet Object Class Code Compatibility Explicit Messaging Function
Parameter Object 0x0F No Single parameter reads/writes
DPI Parameter Object 0x93 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 Safe Speed Monitor option module 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 115 for
instance (parameter) numbering.
Single and scattered parameter reads/writes
Host DPI Parameter Object 0x9F 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-CNET 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 129 for instance (parameter) numbering.
Single and scattered parameter reads/writes