Rockwell Automation 2711-K9A10_K9C10_T9A10_T9C10 DeviceNet Communications User Guide - Manual (Page 12)

12
Publication 2711-6.0.4
I/O Slave Data Exchange
The following diagram shows how data is exchanged using I/O
messaging:
I/O Slave Messaging Notes and Recommendations
• The I/O size specified in the PanelView terminal (“Configuring
DeviceNet Communications” on page 8) must match the I/O size
expected by the DeviceNet scanner.
• COS, Polled and Cyclic are selected during configuration of the
scanner. You do not have to configure the PanelView to accept
COS, polled and cyclic messages.
• Both acknowledged and unacknowledged Change-of-State /
Cyclic modes are allowed. We recommend that you use the
acknowledged COS mode since the device sending the message
never knows that data was received when unacknowledged COS
is used.
• If acknowledged mode is used, no data is returned in the
acknowledgment.
• The Polled + COS option is allowed but the polled response data
and the COS data are from the same assembly. For the most
efficient operation, do not use the Polled + COS option.
• Use of COS or Cyclic I/O connections is highly recommended
over Polled I/O for I/O sizes in excess of 32 words (to minimize
network traffic).
• I/O messages have higher priority than Explicit messaging.
Input Tag
Input Tag
Output Tag
Output Tag
Output Tag
Assembly
Instance 1
Assembly
Instance 2
PanelView
Master Device
(Scanner)
I/O Req
uest M
essage
I/O Mes
sage R
esponse
I/O Slave Tags
I:0
I:63
O:0
O:63
PV Address