User guide

Programming the Drive
4-1
CHAPTER 4
Programming the Drive
This section describes how to program the drive over the ControlNet network.
4.1 About ControlNet Network Communication
The ControlNet network transports time-critical control information (for example, drive
reference and feedback information) as scheduled data, as well as non-time-critical
information (for example, accessing drive parameters) as unscheduled data. The
transportation of the non-time-critical information does not interfere with the time
critical messages.
A node’s access to the network is controlled by a time-slice access algorithm, which
determines a nodes opportunity to transmit in each network update interval. You
configure how often the network update interval repeats by selecting a network update
time (NUT) in milliseconds. The minimum network update time you can specify is
2ms.
The network update time is how often you want to send scheduled traffic. You
configure when a node will transmit during the network update time (scheduled vs.
unscheduled). See table 4.1 for more information about the components of the
network update time.
For optimum throughput, assign addresses to ControlNet nodes in a sequential order.
Table 4.1 – Network Update Time Components
Network Update Time
Component Function
scheduled Information that is
time-critical
(drive reference and
feedback) should be sent during this part of the NUT
interval.
unscheduled Information that
can be delivered without time
constraints
should be sent during this part of the NUT
interval.
The amount of time available for the unscheduled
portion is determined by the traffic load of the scheduled
portion. During this part of the interval, nodes may have
many or no chances to transmit.