2-68 DPI
DPI 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 drives support the existing
SCANport and Drive Peripheral Interface (DPI) communication protocols.
Multiple devices of each type (SCANport or DPI) can be attached to and
communicate with the drive at the same time. This communication interface
is the primary way to interact with, and control the drive.
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/
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