semi合集-English.pdf - 第1522页

SEMI E32-0997 © SEMI 1994 , 1997 17 The HAN DOFF subs tate is divided into two furth er sub sta te s: AW AIT IN G T RAN SFE R P ART NE R AND TRANSFERRING. NOTE: If one transfer partn er has not yet reached th e HANDOFF s…

100%1 / 7923
SEMI E32-0997 © SEMI 1994, 1997 16
4.2.3 Atomic Transfer State Model — When a transfer
job becomes active, it creates a queue of atomic
transfers for each port (see Transition 2 of the transfer
job state model). These atomic transfers are executed as
described in the transfer job state model above. This
section describes the behavior of the atomic transfer as
it is created, executed, and finally deleted.
Figure 4.6 shows the state model for an atomic transfer
as it moves through its life cycle. Each atomic transfer
of an active transfer job is represented by a separate
copy of this state model. These state models are not
substates of the transfer job state model. Rather,
transfer job and atomic transfers are separate entities
which interact.
Figure 4.6
Atomic Transfer State Diagram
The definitions for the states and state transitions
follow.
ATOMIC TRANSFER QUEUED
In this state, the atomic transfer is awaiting its turn to
execute at the port.
TRANSFER ACTIVE
In this state, the transfer job has activated this atomic
transfer. The atomic transfer is performed entirely
within this state. The substates of TRANSFER
ACTIVE are SETUP and HANDOFF.
The TRANSFER ACTIVE state in this model
corresponds to the ATOMIC TRANSFER ACTIVE
state in the transfer job state model. Thus, when the
transfer job activates an atomic transfer on a port, both
state models shall be in the (ATOMIC) TRANSFER
ACTIVE state during the atomic transfer. This applies
only to the specific atomic transfer being performed.
SETUP
While in the SETUP substate, the equipment performs
any pre–transfer setup operations necessary for the
current atomic transfer. These operations might include
(but are not limited to) opening doors, unclamping
carriers, and homing elevators. For transfer agents, it is
reasonable to include as part of the setup such actions
as a transfer agent moving into position near a specified
process equipment.
The setup and restore
8
operations are expected to be
“goal oriented,” that is, oriented toward satisfying
specific conditions (e.g., states such as “door open”).
They should not depend on a fixed sequence of actions
such as “initiate the door opening mechanism.” Thus, a
port left in a post–transfer condition from a previous
atomic transfer would still be able to prepare properly
for the next.
If no setup time is required for the transfer, this state
may be exited immediately. This is the case for a static
port since it can perform no physical actions related to
setup.
HANDOFF
The equipment is committed to the transfer when no
setup operations remain and the port is capable of
performing the transfer. Entry into the HANDOFF state
indicates that the port shall take no further action
without the (expressed or implicit) cooperation of its
transfer partner. Both transfer partners shall be in the
HANDOFF state when the atomic transfer begins.
8 Restore is described in Section 4.2.2.
SEMI E32-0997 © SEMI 1994, 199717
The HANDOFF substate is divided into two further
substates: AWAITING TRANSFER PARTNER AND
TRANSFERRING.
NOTE: If one transfer partner has not yet reached the
HANDOFF substate when the other begins the transfer,
interference could occur on the part of the uncommitted
partner, with potential to damage equipment or
material. The micro level Transfer Ready exchange will
help prevent this (see Section 5 below).
AWAITING TRANSFER PARTNER
Once the port is ready for the transfer, the AWAITING
TRANSFER PARTNER substate is entered. The port
shall remain in this state until its transfer partner is
ready.
TRANSFERRING
In this state, the physical handoff portion of the atomic
transfer is in progress. Most micro level coordination
occurs while the transfer partners are both in the
TRANSFERRING state.
ATOMIC TRANSFER COMPLETE
In this state, the atomic transfer has completed and is
awaiting the completion of the job. Upon entry to this
state, the equipment shall release (deallocate) the port
resources used for this atomic transfer. It shall also
deallocate any material location used by this atomic
transfer that is not needed by any further atomic
transfer in this transfer job. This state exists primarily to
allow the host to poll for current status of the individual
atomic transfers (there is no status if the atomic transfer
no longer exists).
The following transition table defines the transitions
between states for the atomic transfer state model. It
applies to Figure 4.6.
Table 4.2 Atomic Transfer State Transition Table
# Current State Trigger New State Action(s) Comment
1 (Atomic Transfer
Created)
The parent transfer job
becomes active
(see Table 4.1).
ATOMIC
TRANSFER
QUEUED
None. None.
2 ATOMIC TRANSFER
QUEUED
The parent transfer job
selects this atomic transfer
as next for a port and
transitions to ATOMIC
TRANSFER ACTIVE.
SETUP None. None.
3 SETUP All preparation for this
atomic transfer is complete.
AWAITING
TRANSFER
PARTNER
None. “Committed To Transfer” event
occurs. See micro level Transfer
Ready message.
4AWAITING
TRANSFER
PARTNER
Transfer partner is ready
for transfer (see micro
level).
TRANSFERRING None. “Atomic Transfer Started” event
occurs. This transition might not
occur for a static port.
5 HANDOFF The atomic transfer is
completed.
ATOMIC
TRANSFER
COMPLETE
None. The “Atomic Transfer Complete”
event occurs. This transition will
occur after the appearance or
removal of the material at the port.
See the micro level Transfer
Verify message.
6 ATOMIC TRANSFER
COMPLETE
The parent transfer job is
completed.
(Transfer Job
complete)
The atomic
transfer is
deleted.
After this transition, the
equipment maintains no status of
the atomic transition.
SEMI E32-0997 © SEMI 1994, 1997 18
4.3 Extended Behavior Models — In this section, the
concepts of Pause/Resume, Stop/Cancel/Abort, and
AutoStart/StartHandoff are added to the state models
for the transfer job and the atomic transfer. In addition,
the possibility that some transfers will end abnormally
is discussed. While not every implementation requires
these capabilities, all face the prospect of problems
during transfer. This section describes how the basic
state models provided above may be extended to
include such features.
4.3.1 Extended Communications — This section
describes the new commands the host may use to affect
current transfer jobs and the events associated with
these new capabilities.
Pause — The host may issue a command to pause a
transfer job
9
. A command to pause shall cause the
subject to continue to the first safe, continuable pausing
place and then cease activity. The pause shall occur
only at points that allow for the resumption of the
activity (see the resume command). Pausing a transfer
job results in the pausing of each atomic transfer for
that transfer job (see Figure 4.8). The points where a
pause may fall should be defined by the supplier. Note
that a paused transfer job may be aborted or stopped as
an alternative to the resume command. In this case, the
stop command may cause the equivalent of a resume in
order to allow the current atomic transfers to complete.
There are two actions that may cause a pause. The first
is a host command as described in the paragraph above.
The second is a decision by the equipment that a
problem exists that requires outside intervention. For
instance, if a port hardware problem exists, the
equipment may pause the job automatically. The user or
host may then resume the transfer job when the
hardware problem is corrected, or alternately abort/stop
the transfer job if the problem is severe.
Resume — The resume command is used to continue a
previously paused transfer activity.
Stop — The host may command the involved partners
to stop a transfer job. The stop command terminates a
job in an orderly manner. The object of the stop
command is to complete currently executing atomic
transfers and leave the equipment and material in a safe
state. While the time needed to stop should be kept as
short as possible, this goal should be a lower priority.
If the specified transfer job is queued, the stop
command acts as a cancel command.
9 It is expected that a host may also pause a port or other hardware.
However, this document does not specify these hardware-related
commands.
Cancel — The host may cancel a transfer job which has
not yet become active (e.g., a job which is queued).
This is useful when it is unacceptable to affect transfer
which is in–progress. A canceled job is removed from
the queue and discarded. No physical action may be
associated with canceling a transfer job. If the specified
transfer job is active, the equipment shall reject this
command.
Abort — The host may command the involved partners
to abort a transfer job. The goal of the abort command
is to end the transfer activities (especially movement) as
quickly as possible, while retaining equipment and
material integrity. Aborting a transfer job shall cause
the individual atomic transfers to also abort. As with
stop, the abort command terminates the transfer job.
Different from the stop command is that equipment
executing an abort command shall require manual
intervention before further material movement
operations are performed. Abort is intended for use
when serious problems are detected and further damage
needs to be prevented.
The abort command takes precedence over the stop,
pause, and cancel commands. If the specified transfer
job is queued, the abort command acts as a cancel
command.
Transfer Job Create — The Transfer Job Create is not
new, but is extended to include the “AutoStart” option.
There is a parameter added to each atomic transfer
definition which allows selection of this option. If not
selected, the atomic transfer shall enter a WAIT state
after completing SETUP operations, but before
informing its transfer partner that it is ready to begin.
An event signals the host that the equipment is awaiting
instructions.
This feature allows the host added flexibility in
synchronizing material movement activities. The host
may manually synchronize two transfer partners or it
may wish to align a material movement activity with
another equipment or factory-related activity.
StartHandoff — The StartHandoff command is issued
by the host to cause a specific atomic transfer to
transition from the WAIT state to the TRANSFER
ACTIVE state.
4.3.2 Extended Transfer Job State Model — Figure
4.7 presents an extended transfer job state model. This
model provides for the capability to pause/resume, stop,
and abort. Except for the extensions, this model is the
same as that in Figure 4.5. Therefore, only the
extensions are discussed in this section.