Rockwell Automation RECOMM-CNET ControlNet Communications Module - Manual (Page 63)

PLC-5C Applications 6-13
The ControlNet I/O Transfer (CIO) instruction is used to send
Explicit Messages. For PLC-5C controllers before Series F Revision
C, the available services you should use are Get Attribute Single,
Get Attribute All, Set Attribute Single, or Set Attribute All. Series F
Revision C (or later) allow for more complex messages using a new
Generic Bi-Directional communication command.
6.8.2 Explicit Messaging Examples
A Get Attributes Scattered message allows for reading multiple
parameters that may or may not be in sequential order (figure 6.9).
• A Service Code of “4B” indicates the Get_Attributes_Scattered
service (see page C-20, Object Specific Services).).
• A Class Number of “93” indicates accessing the DPI Parameter
Object (see page C-16, DPI Parameter Object).
• An Instance Number of “0” accesses the Class Attributes (see
page C-16, Instances).
• N13:0-11 contains the request message and N14:0-11 contains
the response message (see page C-20, Format for
Get_Attributes_Scattered Service).
Figure 6.8 – Explicit Messaging
This rung sends a message to the drive over ControlNet and receives
file N13 while the response data is placed in data file N14.
the response from the drive. The message to be sent is built in data
000
N7:2
0
User Logic
Message
Initiate
EN
DN
ER
CIO
ControlNet I/O Transfer
Control
CT12:0
Setup Screen
CIO
001 END