User manual

106 Publication ENET-UM001I-EN-P - January 2010
Chapter 7 Interlocking and Data Transfer Between Controllers
Connections for Messages
Messages transfer data to other modules, such as other controllers or operator
interfaces. Each message uses one connection, regardless of how many
modules are in the message path. To conserve connections, you can configure
one message to read from or write to multiple modules.
These connected messages can leave the conn
ection open (cache) or close the
connection when the message is done transmitting.
Cache Message Connections
Message Connections
Type of Message Communication Method Used Connection Used
CIP data table read or write CIP Yes
PLC2, PLC3, PLC5, or SLC (all
types)
CIP No
CIP with Source ID No
DH+ Yes
CIP generic CIP
Your choice
(1)
(1)
You can connect CIP generic messages, but for most applications we recommend you leave CIP generic
messages unconnected.
Block-transfer read or write Yes
Guidelines for Caching Message Connections
Message Execution Instruction
Repeated Cache the connection.
Important: Caching keeps the connection open and op
timizes
execution time. Opening a connection each time the message
executes increases execution time.
Infrequent Do not cache the connection.
Important: Not c
aching closes
the connection upon
completion of the message, freeing up the connection for other
uses.