Rockwell Automation 20D PowerFlex 700S with Phase I Control Reference Manual - Manual (Page 52)

52 Rockwell Automation Publication PFLEX-RM002D-EN-E - August 2013
Chapter 1 Detail Drive Configuration and Operation
The following timing specifications apply to DPI devices:
• Host status messages only go out to peripherals once they log in and at
least every 125 ms (to all attached peripherals). Peripherals will time-out if
more than 250 ms passes without a response. Actual time is dependent on
the number of peripherals attached. The minimum time goal is 5 ms (may
have to be dependent on the Port Baud Rate). DPI allows a minimum 5 ms
status at 125k and 1 ms status at 500k.
• The host determines the Minimum Update Time (MUT) based on the
number of attached peripherals. Range of values from 2 …125 ms.
Minimum goal time of 5 ms. DPI allows 2 ms at 500k and 5 ms minimum
at 125k.
• Peripheral command messages (including Datalinks) generated on change-
of-state, but not faster than Host MUT and at least every 250 ms. Host
will time out if it is more then 500 ms.
• Peer messages requests cannot be sent any faster than 2x of MUT.
• Host must ping every port at least every 2 seconds. Peripherals time if
more then 3 seconds pass. Host will wait a maximum of 10 ms (125k) or
5 ms (500k) for peripheral response to ping. Peripherals typical response
time is 1 ms. Peripherals allow only one pending explicit message (ping
response or peer request) at a time.
• Response to an explicit request or fragment must occur within 1 second or
device will time out (applies to Host or Peripheral). Time-out implies retry
from beginning. Maximum number of fragments per transaction is 16.
Flash memory is exception with 22 fragments allowed.
• During Flash mode, host stops ping, but still supports status/command
messages at a 1…5 second rate. drive will use 1 second rate. Data transfer
occurs via explicit message as fast as possible (i.e. peripheral request, host
response, peripheral request, etc.) but only between two devices.
The MUT, is based on the message type only. A standard command and Datalink
command could be transmitted from the same peripheral faster than the MUT
and still be O.K. However, two successive Datalink commands will have to be
separated by the MUT.
DriveLogix See the DriveLogix 5720 Controller User Manual, publication 20D-UM002 .