SCU-350 Series Control Unit for Turbomolecular Pump
MT-21E-201-E
Page 66
5
SERIAL COMMUNICATION PROTOCOL
5.3.3 SIM replies to queries or commands
When a query or command is received by the SIM, a reply is always returned on the serial link. The
replies sent by the SIM are text messages - sequences of ASCII coded characters terminated by two
control characters CR, LF (ASCII chars 13 [0Dhex], 10 [0Ahex]).
The response from SIM is composed of the character string. It is recommended to receive as the
character string rather than as a number when receiving the response with the communication
equipment (PC).
Note: Put the delay (10ms or more) between the characters. The command cannot be received at
short delays. In this case, the error message replies. Refer to Section 3.6 for details.
Figure 40 - Command syntax
Each query or command must comply with its correct syntax, otherwise an error will be flagged. If a
query or command is syntactically correct then the error number is set to 0.
The reply to a query is normally the ASCII text string representing the number or result of the item
queried. The reply to a faulty query will be a message of the form "ERR n", where "n" is the error
number.
The reply to a command will always be a message of the form "ERR n", if there is no error, the reply
will be "ERR 0". Refer to section 5.4.2 a list of error messages and their meanings.
The last character
!,?
COMMAND CR
The first character
The last character
REPLY CR LF
PC SIM
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