Edwards SCU-1601

SCU-1601 Control Unit for Turbomolecular Pump
MT-96E-1B1-0
Page 85
5
SERIAL COMMUNICATION PROTOCOL
Next, the preceding SIM->PC character is "Ack", the PC continues instructing the control command
(the 2nd block).
PC->SIM
Stx
0
0
2
C
254
C
n
Etx
LRC
SIM->PC
Ack or Nak
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
SIM->PC
Stx
0
0
1
# or !
Etx
LRC
The PC transmits "Ack" or "Nak"; then transmits the next command if necessary.
5.3.4 Query command (in the RS232/RS485 single point connection)
A query command is used to read the pump operation state and setting values. The first character of
the query command in the RS232/RS485 single point connection is "?"(HEX code "3F"), and
succeeding characters are ASCII characters corresponding to the respective function code and
parameter.
?
CHR
C
1
C
2
C
n
CHR: Function code character, C
1
to C
n
: Parameter
Parameter (from C
1
to C
n
) serves as 16 bits signed hexadecimal value coded ASCII text. When a
message (a space character, a function code, and parameter) exceeds 255 characters, input "?" and
CHR to the top transmission block only (the first transmission block of the transmission frame). It is not
necessary to input them to the 2nd and succeeding transmission blocks.
The SIM returns the acknowledgment response character "#" when the query command is processed
normally. If not, the SIM returns the non-acknowledgment response character "!" and 3 characters of
the non-acknowledgment code are added to "!".
Transmission frame when data is transmitted at one block and returned at two blocks:
Designate a query command on the PC
<- Less than 256 chr. ->
PC->SIM
Stx
0
0
1
?
CHR
C
1
C
n
Etx
LRC
SIM->PC
Ack or Nak