SEMI Draft Doc

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Background Statement for SEMI Draft Document 5101

REVISIONS TO SEMI E5-0709E, SEMI EQUIPMENT COMMUNICATIONS STANDARD 2 MESSAGE CONTENT (SECS-II) and
SEMI E30-0307E2, GENERIC MODEL FOR COMMUNICATIONS AND CONTROL OF MANUFACTURING EQUIPMENT (GEM)

Note: This background statement and the line item specific background statements are not part of the balloted item. They are provided solely to assist the recipient in reaching an informed decision based on the rationale of the activity that preceded the creation of this document.

Note: Recipients of this document are invited to submit, with their comments, notification of any relevant patented technology or copyrighted items of which they are aware and to provide supporting documentation. In this context, “patented technology” is defined as technology for which a patent has issued or has been applied for. In the latter case, only publicly available information on the contents of the patent application is to be provided.

Purpose

To propose additions, modifications and/or deletions to the following standards:

SEMI E5-0709E - SEMI Equipment Communications Standard 2 Message Content (SECS-II)
SEMI E30-0307E2 - Generic Model for Communications and Control of Manufacturing Equipment (GEM)

Line item specific background statements are found within each line item definition below.

Impact

The proposals in this document represent a change to the following documents that may have an impact on current implementations.

SEMI E5-0709E
SEMI E30-0307E2

Proposals

This section contains the lines item(s) for this ballot. The following is a summary list of line item(s) contained in this document.

Line Item #1 – E5 and E30 - Correct Max Item Size

The results of this ballot will be discussed at the next North America I&C committee meeting on March 30, 2011 in conjunction with the NA Standards Spring 2011 meetings in San Jose, CA.

SEMI Draft Document 5101

1 Line Item #1– E5 and E30 - Correct Max Item Size

1.1 Background

What is the problem being solved?

E5 Figure 2 “Item and List Header” has a comment for 3 length bytes stating that “3 = Three binary length bytes (max = 7.99M)”.

This limitation of 7.99M bytes was created by an independent standard (E4) rather than the number representable by 24 bits available in 3 bytes.

The limitation of about 7.99M bytes is described in section 9.2.1 of E4.

There is also the matter of the usage of the symbols ‘k’ and ‘M’ in the following text found below figure 2:

2 = Two binary length bytes (max = 64k)

3 = Three binary length bytes (max = 16M).

According to Table 23 of E5:

‘Prefix Symbol ‘k’ is the ‘Prefix Name’ for kilo and the ‘Multiplicative Factor’ for kilo is 10^3.

‘Prefix Symbol ‘M’ is the ‘Prefix Name’ for mega and the ‘Multiplicative Factor’ for mega is 10^6.

Two binary length bytes would allow a length of 2^16-1 = 65,535. This is not 64,000 as indicated by 64k.

Three binary length bytes would allow a length of 2^24-1 = 16,777,215. This is not 16,000,000 as indicated by 16M.

E5 should be consistent with itself so we should not use the symbols in ways that are not accurate.

There is now an alternative protocol for message transmission that does not have the limitations of the E4 message size. This is E37 which is in wide usage.

The current limitation expressed by figure 2 in E5 is an artifact of history that needs to be corrected now that there is the capability to transmit larger messages and larger items within the messages.

E30 section 4.6.3.3.1 also makes reference to this limit: “Process programs and recipes for certain types of equipment, such as metrology or inspection equipment, contain images and are, therefore, very large. Such process programs and recipes cannot fit into a single multi-block SECS-II message that has a maximum theoretical size of 7,995,148 text bytes.” It should be clarified that it is not always necessary to use the E4 multi-block protocol to transmit a SECS-II message now that E37 is available in many factories.

What is the history of this issue and ballot?

This issue was brought to the task force at the fall 2010 task force meeting.

Who will this effect? How? Why?

It is not anticipated that this will affect implementations. It will affect readers of the standard who thought that they were limited to the transmission of recipes or images of size no larger than ~8M as a single item in a SECS-II message. They will be able to see that they can transmit recipes or images up to ~16M as a single item in a SECS-II message.

Is this a change to an existing solution, or, is it a new activity?

This is an update to an existing solution to inform the reader that a potential limitation listed in the standard is smaller than necessary.

Revision Control

This revision control records activity within the task force as well as formal submit and resubmit dates and results per SEMI. Entries have been made by the task force.

Date / Version / Name / Edits
12Nov2010 / 0.1 / David Bricker / First Draft
03 Dec 2010 / 0.2 / David Bricker
Tom Craig
Eberhard Teichmann / Second Draft
20 Dec 2010 / 0.3 / David Bricker / Corrected numeric value for 3 length bytes from 16.78M to 16M.
21 Dec 2010 / 0.4 / David Bricker / Removed inaccurate usage of the byte prefixes k and M.
2 Feb 2011 / 0.5 / David Bricker / There are no outstanding negative comments; the document is approved for balloting.
3 Feb 2011 / 0.6 / Brian Rubow / Changed the wording in the background statement and E30 change to clarify that the limit is on an item within a SECS-II message, not the entire message.

1.2 Proposals

The following proposals apply to this line item.

1.2.1 Proposal

In E0300307E, delete the struck-out text and add the underlined text as shown below:

4.6.3.3.1 Process programs and recipes for certain types of equipment, such as metrology or inspection equipment, contain images and are, therefore, very large. Such process programs and recipes cannot fit into a single multi-block SECS-II message that has a maximum theoretical size of 7,995,148 text bytes. Aprocess program or recipe can not be sent as a single item in a SECS-II message if its size exceeds SECS-II data item size limits as defined in E5, or if the total message size would exceed the SECS message size limits defined in transport protocol standards such as E4 and E37. Furthermore, process programs and recipes may also require some preparation prior to transfer.

1.2.2 Proposal

In E005-0709E, section 9.2.1, figure 2,delete the struck-out text and add the underlined text as shown below:

No. of Length bytes

0 = Illegal, data format error

1 = One binary length byte (max = 255)

2 = Two binary length bytes (max = 64k65,535)

3 = Three binary length bytes (max = 7.99M)

3 = Three binary length bytes (max =16,777,215). Note that transport protocols such as E4 and E37 impose SECS message size limitations that may affect the maximum length of a SECS data item.

1.2.3 Proposal

In E005-0709E, section 4.1, add the following underlined text as shown below:

4.1 SEMI Standards

SEMI E4 – SEMI Equipment Communications Standard 1 Message Transfer (SECS-I)

SEMI E6 – Guide for Semiconductor Equipment Installation Documentation

SEMI E37 –High-Speed SECS Message Services (HSMS) Generic Services

SEMI E148 – Specification for Time Synchronization and Definition of the TS-Clock Object

This is a draft document of the SEMI International Standards program. No material on this page is to be construed as an official or adopted standard. Permission is granted to reproduce and/or distribute this document, in whole or in part, only within the scope of SEMI International Standards committee (document development) activity. All other reproduction and/or distribution without the prior written consent of SEMI is prohibited.

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