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SEMI E30-1103 © SEMI 1992, 2003 62 The host employs the “Date and Time Set Request” message (S2,F31) to initialize th e value of Clock to the value contained in the TIME data item. Sim ilarly, the equipment may employ th…

SEMI E30-1103 © SEMI 1992, 2003

Message fault due to data too long:

COMMENTS HOST EQUIPMENT COMMENTS

Host sends a message. Sx,Fy-->

Equipment detects that the

message from the host contains

more data than it can handle.

<--S9,F11 Equipment reports to the host

that “data too long“ was

detected in the received

message.

Communication Fault Due to Conversation Timeout:

COMMENTS HOST EQUIPMENT COMMENTS

Host sends a message. Sx,Fy-->

<--Sx,Fy+1 Equipment sends reply.

Equipment is now expecting a

specific message from the host

as a result of the previous

transaction. Equipment has not

received the expected message

from the host and a

conversation timeout occurs.

<--S9,F13 Equipment reports to the host

that a conversation timeout

occurred.

4.10 Clock — The clock capability enables host

management of time-related activities and occurrences

associated with the equipment and across multiple

pieces of equipment.

4.10.1 Purpose — The purpose of the clock capability

is to enable time stamping of collection event and alarm

reports. Time stamping is useful for resolving relative

order of event/alarm occurrences and scheduling of

equipment activities by the host.

The ability for the host to instruct the equipment to set

an internal clock to a specified time value, and for the

equipment to request the current date and time, is

needed for effective time management and

synchronization between host and equipment.

4.10.2 Definitions

Clock — Clock is a status variable containing the

current value of time at the equipment. Clock may be

included in report definitions and/or queried separately

by the host. See SEMI E5 for a full definition of this

variable data item and its required formatting.

TIME — TIME is a data item contained in messages

used by the host to set time at the equipment and by the

equipment or host to request the current time from the

other. (See SEMI E5 for a full definition of this data

item.)

4.10.3 Detailed Description — The clock capability

assumes the existence of a relative time reference on

the equipment. This time reference is used as a basis for

updating the time value of an equipment status variable

called “Clock.” The time reference must reflect the

current time to within a resolution range of seconds to

centiseconds (refer to the format for Clock in the SEMI

E5 Standard). The purpose of time stamping with

centiseconds is to resolve the order in which nearly

simultaneous events occur rather than to provide a more

precise record of the time of day at which they

occurred. Where more than one event occurs within a

given period of clock resolution, the centiseconds

reported in the time stamps for these events must reflect

the actual order in which the events were detected.

Equipment with a clock resolution of less than a second

should report centiseconds. Otherwise, centiseconds

should be assigned to reflect the relative order in which

events were detected. Equipment unable to resolve time

to less than a second and unable to reflect the relative

order in which events were detected may report

centiseconds as “00”.

SEMI E30-1103 © SEMI 1992, 2003

The host employs the “Date and Time Set Request”

message (S2,F31) to initialize the value of Clock to the

value contained in the TIME data item. Similarly, the

equipment may employ the “Date and Time Request“

message (S2,F17) to obtain a new initialization time for

Clock. As before, the value of TIME returned by the

host is used to set Clock. Note, in the event that the

precision of TIME is seconds and that for Clock is

centiseconds, in both cases the initial value of Clock

shall contain “00” for its Centisecond digits upon

initialization. Additionally, for any field in TIME that is

not supported by the equipment, the local value of this

field is equipment dependent. For example, Equipment

that cannot resolve time to less than a second might

round or ignore centiseconds and always set the

Centisecond field to “00”.

4.10.4 Requirements

— The resolution and update rate of the internal time

reference must be sufficient to distinguish between

two nearly simultaneous collection events and/or

alarms.

— The equipment supplier shall provide

documentation describing the resolution of the

internal time reference.

— The equipment supplier shall provide

documentation describing how centisecond values

are assigned, including the case of unresolvable

simultaneous events.

4.10.5 Scenarios

Equipment Requests TIME (Optional Scenario):

COMMENTS HOST EQUIPMENT COMMENTS

<--S2,F17 Equipment requests a time value

from the host.

Host responds with a TIME value S2,F18-->

Equipment sets its internal

time reference to the value of

TIME received from the host.

Host Instructs Equipment to Set Time:

COMMENTS HOST EQUIPMENT COMMENTS

Host instructs equipment S2,F31-->

to set its time.

<--S2,F32 Equipment sets its internal

time reference to the value of

TIME received from the host and

acknowledges completion.

Host Requests Equipment’s Current Time Value:

COMMENTS HOST EQUIPMENT COMMENTS

Host requests equipment time. S2,F17-->

<--S2,F18 Equipment returns its internal

time reference value to the

host.

SEMI E30-1103 © SEMI 1992, 2003

4.11 Spooling — Spooling is a capability whereby the

equipment can queue messages intended for the host

during times of communication failure and

subsequently deliver these messages when

communication is restored. Spooling is limited to

primary messages of user-selected streams.

4.11.1 Purpose — The purpose of spooling is to

provide a method for retaining equipment message data

that might otherwise be lost due to communication

failure. The motive for producing this functionality is to

retain valuable data used to track material and to

improve product quality. The spooling capability fills a

gap in the SEMI E5 standard. In the past, without a

spooling capability, the equipment has typically

discarded messages that could not be delivered, or

turned messaging off altogether. It is intended that the

host initiate the spool unload process immediately

following the reestablishment of communications.

4.11.2 Definitions

MaxSpoolTransmit — An equipment constant

containing the maximum number of messages that the

equipment shall transmit from the spool in response to

an S6,F23 “Transmit Spooled Messages” request. If

MaxSpoolTransmit is set to zero, no limit is placed on

the messages sent from the spool. Multi-block

inquire/grant messages are not counted in this total.

OverWriteSpool — A boolean equipment constant used

to indicate to the equipment whether to overwrite data

in the spool area or to discard further messages

whenever the spool area limits are exceeded.

Send Queue — Refers to the queue into which

equipment generated SECS messages are placed in

preparation for transmission to the host.

Spool — The spool is an area of non-volatile storage in

which the equipment stores certain messages that

cannot be delivered to the host (when the equipment is

in the NOT COMMUNICATING substate of

COMMUNICATIONS ENABLED). The spool area

can be thought of as a sequential “ring” buffer. The

term spool is also used to denote the action of placing

messages into the spool area.

SpoolCountActual — A status variable used to keep a

count of the messages actually stored in the

equipment’s spool area. Multi-block inquire/grant

messages are not spooled and not included in this

count.

SpoolCountTotal — A status variable used to keep a

count of the total number of primary messages directed

to the spool, regardless of whether placed or currently

retained in the spool. Multi-block inquire/grant

messages are not spooled and not included in this

count.

SpoolFullTime — A status variable containing the

timestamp when the spool last became full. If the spool

was not filled during the last spooling period, this will

contain a time value prior to the current

SpoolStartTime.

SpoolStartTime — A status variable containing the

timestamp from when spooling was last activated.

4.11.3 Description

4.11.3.1 Spooling State Model — There are two major

states of spooling: SPOOL INACTIVE and SPOOL

ACTIVE. SPOOL ACTIVE has two components:

SPOOL UNLOAD and SPOOL LOAD. These are each

broken into substates. A description of all spooling

states, substates, and applicable state transitions

follows. The POWER OFF and POWER ON parent

states are common to all equipment subsystems. They

are shown here to illustrate the retention of spooling

context during a power down situation.

NOTE 20: Disabling SECS communications does not affect

the current spooling state since no messages are generated

until communications are subsequently enabled. Spooling is

effectively frozen in this case.

POWER OFF

The equipment has lost power for any reason (e.g.,

power failure, power switch set to off).

POWER ON

The equipment is powered up.

SPOOL INACTIVE

This is the normal operating mode. No spooling occurs.

The spool area is empty. Primary SECS-II messages are

transmitted normally.

SPOOL ACTIVE

All primary SECS-II messages ready for sending and

for which spooling is enabled (see S2,F43) are directed

to the spool area. All other primary messages, except

Stream 1, are discarded. The equipment shall attempt to

send any secondary messages that are generated and

discard these messages should the attempt to send fail.

Spool state transitions from SPOOL INACTIVE to

SPOOL ACTIVE if the communications state changes

from COMMUNICATING to NOT COMMUNI-

CATING (Communication State Transition Table, #14)

or from WAIT CRA to WAIT DELAY

(Communication STATE Transition Table, #6).