Hioki BT3562, Инструкция по эксплуатации

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8.4 Communication Methods
112
Compound Com -
mand
Header Omission
When several commands having a common header are combined to form a compound
command (e.g., :CALCulate: LIMit:RESistance:UPPer:
and :CALCulate:LIMit:RESistance:LOWer ), if they are written together in
sequence, the common portion (here, :CALCulate:
LIMit:RESistance ) can be omitted after its initial occurrence.
This common portion is called the "current path" (analogous to the path concept
in computer file storage), and until it is cleared, the interpretation of subsequent
commands presumes that they share the same common portion.
This usage of the current path is shown in the following example:
Full expression
:CALCulate:LIMit:RESistance:UPPer 30000;:CALCulate:LIMit:LOWer 29000
Compacted expression
:CALCulate:LIMit:RESistance:UPPer 30000;LOWer 29000
The current path is cleared when the power is turned on, when reset by key
input, by a colon "
:
" at the start of a command, and when a message terminator
is detected.
Standard command messages can be executed regardless of the current path.
They have no effect upon the current path.
A colon "
:
" is not required at the start of the header of a Simple or Compound
command. However, to avoid confusion with abbreviated forms and operating
mistakes, we recommend always placing a colon at the start of a header.
Output Queue
Response messages are stored in the output queue until read by the controller.
The output queue is also cleared in the following circumstances:
• Power on
• Device clear
• Query Error
The output queue capacity of the instrument is 64 bytes. If response messages
overflow the buffer, a query error is generated and the output queue is cleared.
Also, with GP-IB, if a new message is received while data remains in the output
queue, the output queue is cleared and a query error is generated.
Input Buffer
The input buffer capacity of the instrument is 256 bytes.
If 256 bytes are allowed to accumulate in this buffer so that it becomes full, the
GP-IB interface bus enters the waiting state until space is cleared in the buffer.
The RS-232C interface will not accept data beyond 256 bytes.
This portion becomes the current path, and can be omitted from the messages imme -
diately following.
Output Queue and Input Buffer
Ensure that the no command ever exceeds 256 bytes.
HIOKI BT3562A981-09