Allen-Bradley devicenet modules in logix5000 control systems Manual Do Utilizador

Publication DNET-UM004A-EN-P - March 2004

Control a Device        7-13

If you want to set or get a parameter based on conditions in your 
logic, use a Message (MSG) instruction in ladder logic to access the 
parameter.

Some parameters do not require ongoing updates. For example, 
initializing configuration parameters may occur only when the 
controller goes to run mode. By using a MSG instruction for those 
parameters, you save bandwidth on the DeviceNet network for more 
critical or ongoing data.

In RSNetWorx software, determine the parameter number that you 
want to access:
 

scanner

 controller

device

parameter 1
parameter 2
parameter 3

…
…
…

DeviceNet network

MSG

Logic in the controller

triggers the read or write of

data.

parameter number

means you can only get the value of the

parameter (read-only)

means you can only get the value of the

parameter (read-only)