Edwards STP-iS2207 Series - Control Command in the RS485 Multi-Point Connection

STP-iS2207 Series Turbomolecular Pump
MT-89E-001-C
Page 84
5
SERIAL COMMUNICATION PROTOCOL
5.3.9 Control command in the RS485 multi-point connection
The control command to be used when a pump operation instruction or a setting change instruction is
transmitted to the SIM and is arranged in the order specified below. The top is "Sp" (space character,
HEX code "20") and ASCII characters corresponding to the respective function code and parameter
follow.
Sp 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 "Sp" 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 second and succeeding transmission blocks.
The SIM returns the acknowledgment response character "#" when the control 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 to one block (a message is less than 256 characters):
Designate the control command on the PC.
<- Less than 256 chr.->
PC->SIM @ F
1
F
2
Stx 0 0 1 Sp CHR C
1
C
n
Etx LRC
SIM->PC Ack or Nak F
1
F
2
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 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.
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