Spectrum Controls 1756sc-OF8H Series A - Manual (Page 34)

RSNetWorx must be run to configure ControlNet. Follow these general
guidelines when configuring I/O modules:
1. Configure all I/O modules for a given controller using RSLogix 5000
and download that information to the controller.
2. If the I/O configuration data references a module in a remote chassis,
run RSNetWorx.
Important: RSNetWorx must be run whenever a new module is added
to a networked chassis. When a module is permanently removed from a
remote chassis, we recommend that RSNetWorx be run to optimize the
allocation of network bandwidth.
Direct Connections A direct connection is a real-time data transfer link between the
controller and the device that occupies the slot that the configuration
data references. When module configuration data is downloaded to an
owner-controller, the controller attempts to establish a direct
connection to each of the modules referenced by the data.
If a controller has configuration data referencing a slot in the control
system, the controller periodically checks for the presence of a device
there. When a device’s presence is detected, the controller
automatically sends the configuration data. If the data is appropriate to
the module found in the slot, a connection is made and operation
begins. If the configuration data is not appropriate, the data is rejected
and an error message displays in the software. In this case, the
configuration data can be inappropriate for any of a number of
reasons.
The controller maintains and monitors its connection with a module.
Any break in the connection, such as removal of the module from the
chassis while under power, causes the controller to set fault status bits
in the data area associated with the module. The RSLogix 5000
software may monitor this data area to announce the modules’ failures.
Module Operation In traditional I/O systems, controllers poll input modules to obtain
their input status. Analog input modules in the ControlLogix system
are not polled by a controller once a connection is established. The
modules multicast their data periodically. Multicast frequency depends
on the options chosen during configuration and where in the control
system that input module physically resides. An input module’s
communication, or multicasting, behavior varies depending upon
whether it operates in the local chassis or in a remote chassis. The
following sections detail the differences in data transfers between
these set-ups.