SCU-1601 Control Unit for Turbomolecular Pump
SERIAL COMMUNICATION PROTOCOL
5.3.3 Control command (in the RS232/RS485 single point connection)
A control command is used when transmitting a pump operation command and a setting change
command to the SIM. The first character of the control command in the RS232/RS485 single point
connection 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.
Always assign less than 254 characters (n< 254) to the parameter so that the message is less than
256 characters.
Then the preceding SIM->PC character is "Ack", the instructed control command is executed and the
SIM returns the following response.
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
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