Rockwell Automation 20-750-DNET PowerFlex DeviceNet Option Module - Manual (Page 56)

56 Rockwell Automation Publication 750COM-UM002B-EN-P - October 2012
Chapter 5 Using the I/O
Using Datalinks A Datalink is a mechanism used by PowerFlex drives to transfer data to and from
the controller. Datalinks allow a drive parameter value to be read or written to
without using an Explicit Message. When enabled, each Datalink occupies one
32-bit word in a ControlLogix controller.
The following rules apply when using PowerFlex 750-Series drive Datalinks:
• The target of a Datalink can be any
Host parameter, including those of a
peripheral. For example, drive parameter 535 - [Accel Time 1] can be the
target of any or all option modules installed in the drive.
• The data passed through the drive’s Datalink mechanism is determined by
the settings of the following parameters:
• When an I/O connection that includes Datalinks is active, those Datalinks
being used are locked and cannot be changed until that I/O connection
becomes idle or inactive.
• When you use a Datalink to change a value, the value is not written to the
Nonvolatile Storage (NVS) memory. The value is stored in volatile
memory and lost when the drive loses power. Thus, use Datalinks when
you need to change a value of a parameter frequently.
Datalinks for PowerFlex 750-Series drive peripherals (the embedded EtherNet/
IP adapter on PowerFlex 755 drives only, and option modules such as an encoder
or a communication module) are locked when the peripheral has an I/O
connection with a controller. When a controller has an I/O connection to the
drive, the drive does not allow a reset to defaults, configuration download, or
anything else that could change the makeup of the I/O connection in a running
system. The I/O connection with the controller must first be disabled to allow
changes to the respective Datalinks.
Depending on the controller being used, the I/O connection can be disabled by
doing the following:
• Inhibiting the module in RSLogix 5000 software
• Putting the controller in Program mode
• Placing the scanner in idle mode
• Disconnecting the drive from the network
DeviceLogix Datalinks are also locked while the DeviceLogix program is
running. The DeviceLogix program must first be disabled to allow changes to the
Device Parameter 02 - [DLs From Net Cfg]
Device Parameter 04 - [DLs To Net Cfg]
Host Parameters 01…16 - [DL From Net 01-16]
Host Parameters 17…32 - [DL To Net 01-16]
IMPORTANT A reset is always required after configuring Datalinks so that the
changes take effect.