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SEMI E30-1103 © SEMI 1992, 2003 65 messages only from the spool area until all spooled messages have been completely transmitted to the host. Flow control of the spool transm it process is achieved in two ways. First, on…

SEMI E30-1103 © SEMI 1992, 2003

Figure 4.11

Spooling State Diagram

Once communications are established, the host must

initiate the spool unload sequence to restore full

functionality (see below). Since the equipment will

deliver secondary messages, the host may inquire for

information or send commands as needed.

The SPOOL ACTIVE state has two AND states:

SPOOL LOAD and SPOOL UNLOAD. This means

that they operate independently, though sharing data

and some state change stimuli. See Section 3.1 for

explanation of state model terms and notation.

SPOOL LOAD

The SPOOL LOAD component enters messages into

the spool area. It is divided into two substates: SPOOL

NOT FULL and SPOOL FULL. SPOOL NOT FULL is

the default entry substate of the parent state SPOOL

LOAD.

SPOOL NOT FULL

As primary SECS-II messages are directed to the spool

area, the equipment shall “write” the SECS-II message

to the end of the spool. Status variables

SpoolCountTotal and SpoolCountActual shall be

incremented each time a message is placed in the spool

area.

SPOOL FULL

In this state, all of the allocated spooling area is filled.

Choice of the following options shall be controlled by

the setting of a Boolean equipment constant called

“OverWriteSpool.” The first message to be dealt with is

that which could not be fit into the spool prior to

transition from SPOOL NOT FULL (see transition

table below).

OverWriteSpool is True: The equipment deletes as

many of the “oldest” records (e.g., SECS-II messages)

contained in the spool area necessary to make space for

the new message and then adds the message. Status

variable SpoolCountTotal shall be incremented

whenever a message is submitted to the spool area.

Status variable SpoolCountActual shall be manipulated

to keep an accurate count of the number of messages

contained in the spool area. For example, if it is

necessary to delete three messages in the spool area to

spool one message, SpoolCountActual would have

three subtracted and then one added to the total.

OverWriteSpool is False: Any subsequent primary

messages shall be discarded. When such a message is

discarded, SpoolCountTotal is incremented.

SPOOL UNLOAD

The SPOOL UNLOAD component of SPOOLACTIVE

deals with movement of messages out of the spool. It

has an active substate (SPOOL OUTPUT) and a

passive substate (NO SPOOL OUTPUT). NO SPOOL

OUTPUT is the default entry substate, since the

equipment is NOT COMMUNICATING at the time

spooling is initiated. When communications between

equipment and host are restored, there is an opportunity

for the host to recover spooled messages. No action is

taken until the host initiates the spool output process

via the S6,F23 (Request Spooled Data). The host has

the option to either receive the spooled messages (see

substate TRANSMIT SPOOL) or discard all messages

in the spool (see substate PURGE SPOOL).

NO SPOOL OUTPUT

In this state, no messages are removed from the spool.

SPOOL OUTPUT

The SPOOL OUTPUT state encompasses the removal

of messages from the spool. Its substates are TRANS-

MIT SPOOL and PURGE SPOOL.

TRANSMIT SPOOL

The host elects to receive all messages contained in the

spool area. The equipment is expected to keep track of

the oldest record (i.e., message) within the spool area.

When communications are re-established with the host

and transmission of the spool area is started, the oldest

record must be the first record transmitted, then the

next oldest record, etc. There is no prioritization of

messages to be sent from the spool.

As each spooled message is successfully transmitted to

the host, it is removed from the spool area upon

successful completion of the transaction. Spool-

CountActual is decremented as each message is

removed from the spool. The equipment shall transmit

SEMI E30-1103 © SEMI 1992, 2003

messages only from the spool area until all spooled

messages have been completely transmitted to the host.

Flow control of the spool transmit process is achieved

in two ways. First, only one open transaction on the

equipment is allowed during spool unload. Thus, if a

message requires a reply, the equipment shall wait for

that reply before transmitting the next spooled message.

Messages which require no reply may be transmitted

sequentially as rapidly as the message transfer

mechanism will allow.

The second flow control method is to allow the host to

limit the maximum number of messages sent from the

spool in response to the S6,F23 request. An equipment

constant named MaxSpoolTransmit may be set by the

host to achieve this behavior. If MaxSpoolTransmit is

set to five, for example, the equipment will send the

first five messages from the spool and then transition to

the NO SPOOL OUTPUT state, awaiting the next

S6,F23 request. There is no event report generated

when MaxSpoolTransmit is reached. The host is

responsible for determining this situation by a)

counting the messages received, b) timing out waiting

for the next message, c) inquiring to the equipment for

the curent value of the SpoolCountActual status

variable, or d) some combination of the above. If

MaxSpool-Transmit is set to zero, the spool shall be

transmitted completely in response to S6,F23.

Normal spooling continues during the spool transmit

process. If the SPOOL LOAD component should

transi-tion to SPOOL FULL, it shall not have any effect

on the SPOOL UNLOAD component. Once full, the

spool cannot make the transition back to SPOOL NOT

FULL except via the SPOOL INACTIVE state. Space

made available due to the spool unload process shall

not be used in this case.

When a multi-block message is to be transmitted from

the spool, any required inquire/grant transaction shall

be initiated. If the host’s response denies permission to

send the multi-block message, the equipment shall dis-

card that message and continue with the transmit pro-

cess. This sequence shall count as one message in the

MaxSpoolTransmit count.

There is one area where SPOOL LOAD and SPOOL

UNLOAD may interact: When the spool is full and

OverWriteSpool is True. During the spool transmit pro-

cess, spooled messages are being removed and new pri-

mary messages are being written to the spool. These

new messages are overwriting the oldest messages

available, unless the unload process has freed sufficient

spool space. There is a possibility that the unload and

overwrite processes may compete for control of the

same message area. For example, if the spool holds

messages ABCDE, with A oldest and E newest, A

might be sent to the host, B (and the space from A)

overwritten by the new message F, C sent to the host, D

and E (and the space from message C) overwritten by

G, etc. The loss of continuity may be “disorienting” to

the host program receiving the messages. It is expected

that the unload process will be fast relative to the

generation of new messages, so that this occurrence

will be rare.

Should a communication failure occur during the spool

transmit process, spooling shall continue as before the

transmit process began. However, the spool unload

sequence shall terminate (i.e., transition to NO SPOOL

OUTPUT will occur — see transition table below).

PURGE SPOOL

The equipment shall discard all messages in the spool

and, when the spool is empty, zero SpoolCountActual.

SEMI E30-1103 © SEMI 1992, 2003

Spooling State Transitions

A table follows detailing all spooling state transitions as presented in the state transition diagram.

Table 4.11 Spooling State Transition

# Current State Trigger New State Action Comment

1 SPOOL

INACTIVE

Communication

state changes from

COMMUNICAT-

ING to NOT

COMMUNICAT-

ING or from

WAIT CRA to

WAIT DELAY

and Enable Spool

is true.

SPOOL

ACTIVE

SpoolCountActual and

SpoolCountTotal are ini-

tialized to zero. Any open

transactions with the host

are aborted. SpoolStart-

Time (SV) is set to current

time. Alert the operator

that spooling is active.

The default state in each AND substate

is entered. The message which could

not be sent remains in the send queue

and is dealt with in Spool Active state.

The collection event Spooling

Activated has occurred.

2 SPOOL NOT

FULL

Message generate

which will not fit

into spool area.

SPOOL

FULL

SpoolFullTime (SV) is set

to current time. Alert the

operator that spool is full.

The message which would not fit into

the spooling area is dealt with after the

transition. No collection event is

generated.

3 SPOOL

OUTPUT

Spool area

emptied.

SPOOL

INACTIVE

Spooling process dis-

abled. Alert the operator

that spooling has been

terminated.

The collection event Spooling

Deactivated has occurred. Transition

from the AND substate Spool Unload

component occurs.

4 NO SPOOL

OUTPUT

S6,F23 received

w/RSDC = 1.

PURGE

SPOOL

No action. Initiates purging process. No collection

event is generated since this is based

on host request.

5 NO SPOOL

OUTPUT

S6,F23 received

w/RSDC = 0.

TRANSMIT

SPOOL

No action. Initiates message transmission from

spool. No collection event is generated

since this is based on host request.

6 TRANSMIT

SPOOL

Communication

failure or

MaxSpoolTransmit

reached.

NO SPOOL

OUTPUT

Spool transmission

process suspended.

If communications failure, the event

Spool Transmit Failure has occurred.

No collection event generated for

MaxSpoolTransmit reached.

7 POWER ON Equipment power

source

discontinued.

POWER

OFF

No action. Spooling context has been maintained

in non-volatile storage prior to this

transition.

8 POWER OFF Equipment power

source restored.

POWER ON Spooling context restored

from non-volatile

memory.

If spooling were active prior to power

down, it shall continue. If TRANSMIT

SPOOL were active at powerdown,

transition #6 is expected to follow

since communications state is initially

NOT COMMUNICATING.

4.11.3.2 Enabling Spooling — The equipment shall

provide the host with the ability to enable and disable

Spooling for any message (except Stream 1 messages

(i.e., S1,F1, S1,F13)) via the S2,F43/F44 transaction.

Spooling may be enabled for an entire Stream, for

individual messages within a stream, or for any

combination of the two. Streams and Functions not

referenced in this message are not spooled. Spooling

can be totally disabled by sending an S2,F43 with a

zero length list for the first item (see S2,F43 definition).

In addition, the equipment shall provide an equipment

constant, EnableSpooling, to allow setting the enable or

disable of spooling. NOTE: When EnableSpooling is

false, the SPOOL state cannot transition from

SPOOLINACTIVE to SPOOLACTIVE. Changing

EnableSpooling does not change the spool state, purge

the spool or change streams and functions enabled for

spooling. Once the equipment is “SPOOL ACTIVE”,

the host must initiate the spool unload sequence to