STP-iS2207 Series Turbomolecular Pump 
 
MT-89E-001-C
Page 86 
5
SERIAL COMMUNICATION PROTOCOL 
Always assign less than 254 characters (n< 254) to the parameter so that the message is less than 
256 characters. 
Next, the preceding SIM->PC character is "Ack", the instructed query command is executed and the 
SIM returns the following response (1st block). 
PC->SIM
                            Ack or Nak  F
1
F
2
SIM->PC
@
F
1
F
2
Stx
0
0
1
Sp
CHR
C
1
  C
253
Etb
LRC
     
 
Then "Ack" is sent by the PC->SIM character in reaction to the response (1st block) from the SIM, the 
SIM returns the following response (2nd block). 
PC->SIM
 
          Ack or Nak  F
1
F
2
SIM->PC
@
F
1
F
2
Stx
0
0
2
C
254
  C
n
Etx
LRC
 
 
The PC transmits "Ack" or "Nak"; then transmits the next command if necessary. 
 
5.3.11  Broadcasting command in the RS485 multi-point connection 
The  START  or  STOP  of  STP  pump  operation  command  can  be  concurrently  instructed  to  all  the 
multi-connected SIMs. Always assign 0 (HEX code "30") to network frame number. Note that there is 
no response from the respective SIM. 
PC->SIM
@
0
0
Stx
0
0
1
Sp
E
Parameter 1
Etx
LRC
 
SIM->PC
 
 
      No response
 
Parameter
Item  Data Format  Remark 
1  Pump operation command  8-bits hexadecimal 
coded ASCII 
Refer to Table 21 
 
Pump operation command
Value 
START  1 
STOP  2 
Table 21 - Pump operation commands