Drive Overload - Allen-Bradley PowerFlex 70 Reference Manual

Drive Overload

Drive Overload
94
Table 12 Timing specifications contained in DPI and SCANport
DPI Host status messages only go out to peripherals once they log in and at least every 125ms (to all
attached peripherals). Peripherals time out if >250ms. Actual time dependent on number of
peripherals attached. Minimum time goal of 5ms (may have to be dependent on Port Baud Rate). DPI
allows minimum 5ms status at 125k and 1ms status at 500k.
SCANport Host status messages only go out to peripherals once they log in. Peripherals time out if >500ms. If
Peripheral receives incorrect status message type, Peripheral generates an error. Actual time
dependent on number of peripherals attached. SCANport allows minimum rate of 5ms.
DPI Host determines MUT based on number of attached peripherals. Range of values from 2 to 125ms.
Minimum goal time of 5ms. DPI allows 2ms min at 500k and 5ms min at 125k.
SCANport No MUT.
DPI Peripheral command messages (including Datalinks) generated on change-of-state, but not faster
than Host MUT and at least every 250ms. Host will time out if >500ms.
SCANport Command messages produced as a result of Host status message. If no command response to Host
status within 3 status scan times, Host will time out on that peripheral.
DPI Peer messages requests cannot be sent any faster than 2x of MUT.
SCANport No Peer message support
DPI Host must ping every port at least every 2 sec. Peripherals time out if >3 sec. Host will wait maximum
of 10ms (125k) or 5ms (500k) for peripheral response to ping. Peripherals typical response time is 1ms.
Peripherals only allow one pending explicit message (i.e. ping response or peer request) at a time.
SCANport Host waits at least 10ms for response to ping. Host cannot send more than 2 event messages (including
ping) to a peripheral within 5ms. Peripherals typical response time is 1ms.
DPI Response to an explicit request or fragment must occur within 1 sec 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.
SCANport Assume same 1 sec time-out. Maximum number of fragments is 16
DPI During Flash mode, host stops ping, but still supports status/command messages at a 1 – 5 sec rate.
Drive will use 1 sec 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.
SCANport No Flash mode support
The Minimum Update Time (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. Two successive Datalink
commands or standard commands will still have to be separated by the MUT,
however.
The drive thermal overload has two primary functions. The first requirement is
to make sure the drive is not damaged by abuse. The second is to perform the first
in a manor that does not degrade the performance, as long the drive temperature
and current ratings are not exceeded.
The purpose of is to protect the power structure from abuse. Any protection for
the motor and associated wiring is provided by a Motor Thermal Overload
feature.
The drive will monitor the temperature of the power module based on a
measured temperature and a thermal model of the IGBT. As the temperature
rises the drive may lower the PWM frequency to decrease the switching losses in
the IGBT. If the temperature continues to rise, the drive may reduce current limit
to try to decrease the load on the drive. If the drive temperature becomes critical
the drive will generate a fault.
Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013