Edwards STP-iXA4507 Series - Page 84

STP-iXA4507 series Turbomolecular Pump
MT-91E-001-0
Page 74
SERIAL COMMUNICATION PROTOCOL
PAG
E
74
5
The network frame number is specified as 1 to 127 by 16 bit signed hexadecimal value coded ASCII
to identify the SIM.
Examples: A Network frame ID character and number in the multi-point connection
ASCII
@
0
1
Network frame No "1"
HEX
40
30
31
ASCII
@
6
4
Network frame No "100"
HEX
40
36
34
ASCII
@
7
F
Network frame No "127"
HEX
40
37
46
The transmission frame has a single block or multiple transmission blocks. Each transmission block
consists of a network frame ID character, a network frame number, a start control character, a data
block number (3 digits), a message (up to 255 characters), an end control character, and a
checksum (LRC). The following shows a transmission frame when the message transmission
character string is C
n
.
Transmission frame when a message is below 255 characters (n<=255):
1
2
3
4
5
6
7
8
8+n
8+n+1
8+n+2
ASCII
@
F
1
F
2
Stx
0
0
1
C
1
C
n
Etx
LRC
"@" is used as a network frame ID character.
"Stx" and "Etx" are used as the transmission frame's start and end characters, respectively.
Transmission frame when a message exceeds 255 characters (n = 255, m<=255, k = the number of
transmission blocks)
First
1
2
3
4
5
6
7
8
8+n
8+n+1
8+n+2
Block
ASCII
@
F
1
F
2
Stx
0
0
1
C1
1
C1
n
Etb
LRC
Second
1
2
3
4
5
6
7
8
8+n
8+n+1
8+n+2
Block
ASCII
@
F
1
F
2
Stx
0
0
2
C2
1
C2
n
Etb
LRC
Final
1
2
3
4
5
6
7
8
8+m
8+m+1
8+m+2
Block
ASCII
@
F
1
F
2
Stx
k
Ck
1
Ck
m
Etx
LRC
"@" is used as a network frame ID character.
"Stx" is the start character of each transmission block, and "Etb" is the end character of the
transmission block of a message of 255 characters.
"Etx" is the end character of the final transmission block (end character of the transmission frame).