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SEMI E4-0699 © SE MI 1980, 1999 11 Figure 4 Message Receive Algorithm

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SEMI E4-0699 © SEMI 1980, 1999 10
Table 4 Protocol Parameters
Symbol Parameter Name Typical Function Typical Value Range Resolution
BAUD Baud Rate Sets serial line speed 9600 300 - 9600 see Section
3.3
DEVID Device ID Identifier assigned to the equipment — 0 - 32767 1
T1 Inter-Character Timeout Detects an interruption between characters 0.5 sec. 0.1-10 sec. 0.1 sec.
T2 Protocol Timeout Detects a lack of protocol response 10 sec. 0.2-25 sec. 0.2 sec.
T3 Reply Timeout Detects a lack of reply message 45 sec. 1-120 sec. 1 sec.
T4 Inter-Block Timeout Detects an interruption in a multi-block message 45 sec. 1-120 sec. 1 sec.
RTY Retry Limit The maximum number of send retries allowed 3 0 - 31 1
M/S Master Slave Contention resolution — — —
9 Documentation
9.1 For equipment or host to comply with SECS-I, a
document is required containing the following
information. (See also SEMI E6, Facilities Interface
Specifications Guideline and Format.)
1. Method for setting all the parameters in Table 4.
2. Range allowed and resolution for each parameter in
Table 4.
3. Compatibility with duplicate block detection and
the method for enabling and disabling the same if
present (see Section 7.4.2).
4. Maximum expected inter-character, protocol, reply,
and inter-block delays generated under normal
operating conditions.
5. Whether multi-block messages are supported as a
receiver.
6. Whether multi-block messages are used as a
sender.
7. Whether there is a limit to the size of a message
received and, if so, what the limit is.
8. Maximum expected size of a message being sent.
9. Whether message interleaving is supported as a
receiver.
10. Whether message interleaving is used as a sender.
11. Number of device ID's supported on the port.
12. Maximum number of supported concurrent open
transactions.
SEMI E4-0699 © SEMI 1980, 199911
Figure 4
Message Receive Algorithm
SEMI E4-0699 © SEMI 1980, 1999 12
APPENDIX 1
A1-1 Differences from SECS-I 1980
This appendix describes the major differences between
this version of the standard and the version originally
adopted in 1980.
A1-1.1 Signal Connections — The required voltage
levels for pins 18 and 25 on the 25 pin "D" connector
are now optional.
A1-1.2 Data Rate — The 150 baud data rate has been
made optional.
A1-1.3 Timeout Parameters — The T4 timeout, which
limits the inter-block arrival time of multi-block
messages, has been added. Use of the T3 timeout has
been clarified.
A1-1.4 Time Before Length Byte — The protocol time
with limit T2 is now used while waiting for the length
byte after sending an EOT.
A1-1.5 Block Send Acknowledgment — Any character
other than an ACK received after sending the second
checksum byte is treated as an NAK.
A1-1.6 Illegal Block Lengths and Bad Checksums —
An NAK code is sent for an illegal block length or for a
bad checksum, but only after waiting for the sender to
stop sending by forcing an inter-character (T1) timeout.
A1-1.7 Block Number — The wording describing the
block number has been clarified to say that the value,
zero, is allowed only for single block messages.
A1-1.8 System Bytes — The handling of the system
bytes for secondary messages sent by a host is now the
same as for the equipment. Also, specific functional
requirements have been added for the content of the
system bytes field.
A1-1.9 Duplicate Blocks — A mechanism for the
detection of duplicate blocks has been added.
A1-1.10 Messages — The discussion of message
assembly from blocks has been clarified and expanded.
A1-1.11 Transactions — The discussion of transaction
handling and reply linking has been moved from SECS-
II and expanded.
A1-1.12 Appendix — Parts of the Appendix have been
moved to a new section called Related Information to
distinguish the content from the standard itself. The
general node transaction flow chart has been moved
from the Appendix in SECS-II to the Related
Information in SECS-I.
A1-1.13 Titles — The title of SECS-I has been
changed from "Data Link" to "Message Transfer." This
phrase more accurately covers the content of the
standard and avoids confusion with other uses of the
term "data link." The title of the "Data Link" section of
SECS-I has been changed to "Block Transfer." The
"Data Link Control" portion of the Block Transfer
Protocol has been retitled "Line Control."
A1-1.14 W-Bit — The W-bit is now required to be set
consistently in all blocks.
A1-1.15 Documentation — A section has been added
on the documentation required for compliance with the
standard.