Dpi - Allen-Bradley PowerFlex 70 Reference Manual

DPI

DPI
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Drive Peripheral Interface (DPI) is an enhancement to SCANport that provides
more functions and better performance. SCANport was a CAN based,
Master-Slave protocol, created to provide a standard way of connecting motor
control products and optional peripheral devices together. It allows multiple (up
to 6) devices to communicate with a motor control product without requiring
configuration of the peripheral. SCANport and DPI both provide two basic
message types called Client/Server (C/S) and Producer/Consumer (P/C).
Client/Server messages are used to transfer parameter and configuration
information in the background (relative to other message types). Producer/
Consumer messages are used for control and status information. DPI adds a
higher baud rate, brand specific enabling, Peer-to-Peer (P/P) communication,
and Flash Memory programming support. PowerFlex 70 & 700 support the
existing SCANport and DPI communication protocols. Multiple devices of each
type (SCANport or DPI) can be attached to and communicate with PowerFlex
70 & 700 drives at the same time. This communication interface is the primary
way to interact with, and control the drive.
Important: The PowerFlex 700 Vector Control option only supports the DPI
communication protocol. It will not communicate with SCANport
peripheral devices.
Client/Server
Client/Server messages operate in the background (relative to other message
types) and are used for non-control purposes. The Client/Server messages are
based on a 10ms "ping" event that allows peripherals to perform a single
transaction (i.e. one C/S transaction per peripheral per time period). Message
fragmentation (because the message transaction is larger than the standard CAN
message of eight data bytes) is automatically handled by Client/Server operation.
The following types of messaging are covered:
• Logging in peripheral devices
• Read/Write of parameter values
• Access to all parameter information (limits, scaling, default, etc.)
• User set access
• Fault/Alarm queue access
• Event notification (fault, alarm, etc.)
• Access to all drive classes/objects (e.g. Device, Peripheral, Parameter, etc.)
Producer/Consumer operation overview
Producer/Consumer messages operate at a higher priority than Client/Server
messages and are used to control/report the operation of the drive (e.g. start, stop,
etc.). A P/C status message is transmitted every 5ms (by the drive) and a
command message is received from every change of state in any attached DPI
peripheral. Change of state is a button being pressed or error detected by a DPI
peripheral. SCANport devices are slightly different in that those peripherals
transmit command messages upon reception of a drive status message rather than
on detection of a change of state. Producer/Consumer messages are of fixed size,
Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013