STP-iXR1606 Turbomolecular Pump
MT-79E-001-D
Page 81
5
SERIAL COMMUNICATION PROTOCOL
Transmission frame when a message exceeds 255 characters (n = 255, m<=255, k = the number of
transmission blocks):
"Stx" is used as a start character of each transmission block; "Etb" is used as an end character of the
transmission block with a message of 255 characters; "Etx" is used as an end character of the final
transmission block (the end character of the transmission frame).
5.3.3 Control command (in the RS232/RS485 single point connection)
A control command is used when transmitting a pump operation commands and a setting change
commands to the SIM. The first character of the control command is "Sp" (a space character, HEX
code "20"), and succeeding characters are ASCII characters corresponding to the respective function
code and parameter.
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.
PC->SIM
SIM->PC
Always assign less than 254 characters (n< 254) to the parameter so that the message is less than
256 characters.
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