STP-iXR1606 Turbomolecular Pump
MT-79E-001-D
Page 83
5
SERIAL COMMUNICATION PROTOCOL
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
C
Etx LRC
SIM->PC Ack or Nak
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
SIM->PC Stx 0 0 1 Sp CHR C
C
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
SIM->PC Stx 0 0 2 C
C
Etx LRC
The PC transmits "Ack" or "Nak"; then transmits the next command if necessary.
5.3.5 Transmission data format
Data value is always 16 bits signed hexadecimal value coded ASCII text.
Example: 12090 on a decimal basis equals to 2F3A on a hexadecimal basis.
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