2-84 DPI
message rather than on detection of a change of state. Producer/Consumer
messages are of fixed size, so support of message fragmentation is not
required. The following types of messaging are covered:
• Drive status (running, faulted, etc.)
• Drive commands (start, stop, etc.)
• Control logic parsing operations (e.g., mask and owner parameters)
• Entering Flash programming mode
• “Soft” login and logout of peripheral devices (enabling/disabling of
peripheral control)
Peer-to-Peer operation
Peer-to-Peer messaging allows two devices to communicate directly rather
than through the master or host (i.e. drive). They are the same priority as C/
S messages and will occur in the background. In the PowerFlex 70 drive, the
only Peer-to-Peer functionality supports proxy operations for the LED HIM.
Since the PowerFlex 700 drive does not support an LED HIM, it will not
support Peer-to-Peer proxy operations. The Peer-to-Peer proxy operation is
only used so that the LED HIM can access parameters that are not directly
part of the regulator board (e.g. DeviceNet baud rate, etc.). The LED HIM is
not attached to a drive through a CAN connection (as normal DPI or
SCANport devices are), so a proxy function is needed to create a DPI
message to access information in an off-board peripheral. If an LCD HIM is
attached to the PowerFlex 70 or 700 drive, it will be able to directly request
off-board parameters using Peer-to-Peer messages (i.e. no proxy support
needed in the drive). Because the PowerFlex 70 supports the LED HIM,
only 4 communication ports can be used. PowerFlex 700 drives can use all 6
communication ports because Peer-to-Peer proxy operations are not needed.
All Peer-to-Peer operations occur without any intervention from the user
(regardless whether proxy or normal P/P operation), no setup is required.
No Peer-to-Peer proxy operations are required while the drive is in Flash
mode.
All the timing requirements specified in the DPI and SCANport System,
Control, and Messaging specifications are supported. Peripheral devices
will be scanned (“pinged”) at a 10ms rate. Drive status messages will be
produced at a 5ms rate, while peripheral command messages will be
accepted (by the drive) as they occur (i.e. change of state). Based on these
timings, the following worst case conditions can occur (independent of the
baud rate and protocol):
• Change of peripheral state (e.g. Start, Stop, etc.) to change in the drive –
10ms
• Change in reference value to change in drive operation – 10ms
• Change in Datalink data value to change in the drive – 10ms
• Change of parameter value into drive – 20ms times the number of
attached peripherals
The maximum time to detect the loss of communication from a peripheral
device is 500ms.
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