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SEMI E32-0997 © SEMI 1994 , 1997 11 Figure 4.1 Transfer Job Seque ncing There are ex ceptions to th e sequencing gui deli nes above. One case w o uld be a devi ce designed to simultaneousl y transfer from multiple por ts…

SEMI E32-0997 © SEMI 1994, 1997 10

manner to other types of recipes on the equipment (e.g.,

process recipes).

4.1.6 Transfer System Controller as Transfer Agent —

A transfer agent is an entity to which transfer-related

commands are given in order to carry out transfer jobs.

A transfer system, which might include several material

transport devices, can be described the same way.

However, there are some important differences.

There are a number of ways that a host could view a

transport system, including:

• as a single transfer agent with numerous ports,

• as a single transfer agent with a single port and

numerous internal locations,

• as multiple logical transfer agents with their own

ports, or

• as the set of real transfer agents that the transfer

system controls.

The transfer system may conceal from the host the

various internal operations (e.g., handoffs, travel paths)

that it uses to complete a transfer. It may even hide the

actual physical location (or series of locations) and

provide a logical location for host reference.

4.1.7 Transfer Job — The host's material transfer

objectives are defined in a transfer job. This transfer job

may be a single atomic transfer or a compound transfer.

A compound transfer job consists of multiple atomic

transfers grouped together to accomplish a more

complex objective. A typical compound transfer may

also be accomplished by creating a separate transfer job

for each required atomic transfer. The decision to group

atomic transfers into a transfer job is application-

dependent.

The key advantages to the use of compound transfer

jobs are the reduction of the communication overhead

to the host and the streamlining of the transfer process.

The communication overhead is reduced by the fact that

the host can define a number of atomic transfer

operations with a single message to the equipment. The

equipment are not required to wait for host commands

between these atomic transfers.

The process is streamlined by virtue of the removal of

redundant physical activities during the transfer job.

Total setup and restore time for a port may be reduced

if the setup for consecutive atomic transfers is similar.

One example of streamlining would be the “exchange”

of carriers between equipment, where a transfer agent

might bring an empty carrier to replace a full carrier on

the “output port” of a machine. If the port has a door

that is opened during transfer preparation and closed

during the restore phase, the door would be better left

open for both atomic transfers. Upon completion of the

removal of the first transfer object, rather than close the

door, the new transfer is begun and the door left open.

The two atomic transfers would thus be executed as one

smooth “swap” transfer without wasted time.

Equipment View of Transfer Job — A transfer job may

involve a number of equipment and ports. Each of the

involved equipment is given a Transfer Job Create

request that specifies only the portion of the overall

transfer job that involves that equipment. Only the host

is guaranteed a complete picture of a compound

transfer. In the example where a transfer job was

created to move a transfer object from “X” to “Y” via

transfer agent “T,”

• “X” would see send material to “T,”

• “Y” would see receive material from “T,” and

• “T” would see get material from “X” and put

material on “Y.”

Atomic Transfer Sequencing Guidelines — When the

transfer job given to an equipment contains multiple

atomic transfers, the guidelines for performing those

transfers are:

• Atomic transfers for a specified port are performed

in the sequence given.

• When a transfer job references multiple ports on

the equipment, these ports may execute their

atomic job sequences in parallel to the other ports.

See Figure 4.1 for an illustration of the flow of a

complex transfer job from the view of one equipment.

The three parallel paths show a possible chronology for

a transfer job.

SEMI E32-0997 © SEMI 1994, 199711

Figure 4.1

Transfer Job Sequencing

There are exceptions to the sequencing guidelines

above. One case would be a device designed to

simultaneously transfer from multiple ports on one

machine to corresponding ports on another. This would

translate into synchronized parallel atomic transfers on

separate ports. Another case would be two atomic

transfers involving the same port that might happen

concurrently. That is, a transfer object is transferred out

of the port at the same time

another is transferred in.

In either of these cases, the equipment is responsible

for:

1. recognizing that such transfers can and should be

combined and

2. synchronizing the execution of the transfers.

Multiple Transfer Jobs — Multiple transfer jobs may

exist simultaneously on an equipment. Although not a

requirement, an equipment may

1. queue transfer jobs for later execution or

2. allow them to execute in parallel with other

transfer jobs.

4 “At The Same Time” in this case means that both atomic transfers

are in progress. It does not imply that both transfer objects must move

simultaneously.

Queued transfer jobs and parallel transfer jobs are

separate concepts, either of which may be supported.

Resource Allocation/Deallocation — Transfer jobs

allocate the needed material locations prior to

beginning. These material locations remain allocated

until the transfer job chooses to release them. In many

cases, a material location is physically linked with a

single port, and the allocation of that location infers

allocation of the port. However, this is not a

requirement.

If the material locations for a transfer job are not

available or are not in the proper state, the job shall be

rejected or queued (if queuing supported and queue not

full). For the transfer job to begin, each location

referenced in the equipment's transfer job must contain

the proper material for the first atomic transfer which

would use that location.

If parallel transfer jobs are supported and the necessary

locations are available, a second (or third, etc.) transfer

job may begin execution.

In some cases a port may provide direct access to

multiple locations. This may be true for the specialized

ports described in Section 3.2 and in cases where the

port serves as a pass–through to internal locations. For

each atomic transfer, the needed port and its resources

are allocated just prior to the start and released

(deallocated) at the end of that atomic transfer.

4.2 Macro Level Behavior

4.2.1 Macro Level Communications — This section

provides a high-level definition of the communications

between the host and each transfer partner needed to

achieve the macro level of material transport. This is

not intended to define the messages, but rather to

describe the concepts. The message detail is addressed

in the Macro Level Services Section (4.4). Section 4.2.2

shows how these messages are integrated into the

transfer job behavior model.

First, the control message flow is presented as Figure

4.2. Then additional informational messaging is

described (see Figure 4.3). The arrows represent

significant information exchange. Some replies that do

not contain significant information may not be shown.

The ordering of the messages between one partner and

host shall be retained. The key synchronization point

between the partners at the macro level is that both

partners shall complete their setup activities before the

“atomic transfer started” event may occur.

4.2.1.1 Macro Level Job Control — Figure 4.2

illustrates the job control-related message flow

expected on a normal transfer as seen by the host.

These messages are used to control the material

movement process. This diagram assumes a simple

transfer job involving only two partners and only one

port on each. It also assumes that the partners take the

same role (primary or secondary) for each atomic

transfer that occurs. The messaging is no different if

these assumptions are not made, but diagrams become

quite difficult to create.

Figure 4.2

Macro Level Message Flow

Transfer Job Create — The host requests that the device

participate in a specified transfer job. This may consist

of a single atomic transfer or a compound job. This

request may be acted upon immediately, or, if necessary

resources are currently busy, saved for later execution

The request shall supply a transfer specification for

each atomic transfer, in which the host supplies such

information as

• which port is to be used,

• whether the port is to send or receive material,

• identification of the material to be transferred,

• role of the equipment (primary or secondary

transfer partner),

• mechanism or recipe to be used in the transfer,

• identification of the other transfer partner, and

• an identifier for the atomic transfer.

Upon receipt of the Transfer Job Create request and

before acknowledging, the equipment should check the

transfer specification(s) to ensure that they are valid.

That is, that the specified parameters (ports, transfer

recipes, role of the equipment, etc.) have legal values.

Depending upon its ability to queue jobs, it may check

such dynamic information as presence of transfer

5 If the equipment does not support queuing or if the queue is full, the

request may be rejected.

object, availability of resources, etc. to determine

whether to accept or reject.

Transfer Job Create Acknowledge — The equipment

responds to the host that the requested job is accepted

or rejected, and if rejected, supplies the reason.

Transfer Job Complete — Once a transfer partner

completes the restore operation, it declares the transfer

job to be complete. This message is also used should a

transfer job end abnormally. It declares the end of job.

All movement of the involved mechanisms shall have

ceased before this message is sent. This message shall

provide information on the success or failure of the

transfer.

Transfer Job Started — This message marks the

beginning of the transfer job. It signifies that the setup

activities for the first atomic transfer are beginning.

Get Attribute — The host may request information

relating to a specific job. This may include portions of

the transfer specification and current status information.

4.2.1.2 Macro Level Information Messaging — There

are a number of material transfer-related events which

may be of significance to the host. These are designated

as “collection events” and shall be available for

reporting to the host. This section describes those

collection events and shows how they fit into the

chronology of a transfer job. Refer to Figure 4.3 as each

event is described.

Collection event messages provide valuable

information to the host, but are not strictly required to

perform material movement. Therefore, it is expected

that some message protocol implementations will

provide a method by which the factory host may disable

those events which are not needed in a particular

implementation.

Figure 4.3

Macro Level Messaging With Events