Asyst Technologies VersaPort 2200, Техническое руководство

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Page 140 2000-1252-01 Released Rev. C
VersaPort 2200 Technical Manual
Appendix B: Communications Software
SECS Communication
a
high-order bit (bit 15) of the field is called the W-bit. This bit defines whether a
reply is expected. If the W-bit is 0, a reply is not expected. If the W-bit is 1, a reply
is expected.
Block number (2 bytes) . A sequence field specifies a particular block within a
multi-block series.
System bytes (4 bytes) . System bytes are reserved for bookkeeping information
by the message originator. For the case where a reply is required from the
VersaPort, the same system bytes will be used in the reply header.
Checksum Bytes . The checksum is calculated as a simple 16-bit unsigned sum
of all the bytes in the header and text. The checksum is initialized to zero. Any
overflows are ignored. The checksum is transmitted as two bytes, with the more
significant byte first.
• Text (0 to 244 bytes)
• Checksum (2 bytes)
The minimum size block consists of a header and no text. With the length byte and
checksum, the block has 13 bytes.
The maximum size block consists of a header (10 bytes) and text. The length byte
specifies 254 bytes (text + 10). With the length byte (1 byte) and checksum (2 bytes), the
block has a total of 257 bytes.
SECS Messages
NOTE . . .
I
N THE FOLLOWING MESSAGES
, S_,F_
INDICATES
S
TREAM AND
F
UNCTION
. * S
INDICATES A SINGLE BLOCK
, H
SIGNIFIES THE
H
OST
/P
ROCESS
T
OOL
, E
SIGNIFIES THE
E
QUIPMENT
/V
ERSA
P
ORT
,
AND THE ARROW SIGNIFIES THE
DIRECTION OF THE COMMUNICATION
.
T
ABLE
19 SECS Message Summary
Stream &
Function
Code
Description
Direction of
communication
S1, F0 Abort Transaction *S,H
↔
S1,F1 Are you there request (R) *S,H
→
E, reply
S1,F2 On line Data (D) *S,H
←
E
S1,F5 Formatted Status Request (FSR) *S,H
→
E, reply
S1,F6 Formatted Status Data (FSD) *S,H
←
E
S2,F13 Equipment Constant Request (ECR) *S,H
→
E, reply
S2,F14 Equipment Constant Data (ECD) *S,H
←
E