Edwards SCU-800 - Page 86

SCU-800 Control Unit for Turbomolecular Pump
MT-49E-101-G
Page 74
5
SERIAL COMMUNICATION
PROTOCOL
Transmission frame when data is transmitted to two blocks (message is more than 256 characters
and less than 512 characters):
Designate the control command (the 1st block) on the PC.
PC->SIM
@
F
1
F
2
Stx
0
0
1
Sp
CHR
C
1
C
253
Etb
LRC
SIM->PC
Ack or Nak
F
1
F
2
Next, the preceding SIM->PC character is "Ack", the PC continues instructing the control command
(the 2nd block).
PC->SIM
@
F
1
F
2
Stx
0
0
2
C
254
C
n
Etx
LRC
SIM->PC
Ack or Nak
F
1
F
2
Always assign less than 510 characters (n< 510) to the parameter so that the message is less than
512 characters.
Then the preceding SIM->PC character is "Ack", the instructed control command is executed and the
SIM returns the following response.
PC->SIM
Ack or Nak
F
1
F
2
SIM->PC
@
F
1
F
2
Stx
0
0
1
# or !
Etx
LRC
The PC transmits "Ack" or "Nak"; then transmits the next command if necessary.