Installation guide

Estimating Network Performance
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During dequeueing at the destination, the receiving node will request
the command again from the originating node when the receiving node
acquires the network token. The command is reissued and received
while the receiving node holds the token.
This process eliminates the need for continual polling, reducing the
overhead in your application and the loading that would be caused by
polling on the network. It does, however, tend to add some loading and
to decrease the overall message throughput. By adopting techniques to
minimize queueing, such as logically grouping the nodes on each
network, using global data transactions, and packing more data into
fewer MSTR transactions, you can achieve fast response times and high
data rates in your process.
3.10.2 Modbus Port Data Path Handling Under Loading
The dedicated Data Master path for a controller’s Modbus port in
bridge mode is always available. Transactions are given to the peer
processor as received from the master device connected to the port, and
are transmitted when the token is acquired.
Data Slave paths in the receiving device will be queued as necessary if
multiple messages are initiated to the same device.
3.10.3 Program Path Handling Under Loading
Program Master and Program Slave paths are not queued. Only one
programmer can have access to a controller at any given time. An
attempt to attach a second programmer will return an error message to
that device.