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3.1 Messages
Response Message
Data that is sent from the instrument to the controller
are called response messages. The response
message format is shown below.
;
<Response message unit>
<Response Message Unit>
A response message consists of one or more
response message units; each response message unit
corresponds to one response.
Response message units are separated by a
semicolon (;).
For details regarding the format of the response
message unit, see page 3-4.
Example
:SAMPLE:GATE:MODE EXTERNAL;POLARITY POSITIVE<RMT>
Unit
<RMT>
A response message terminator. It is NL^END.
• Response Message Unit Format
The response message unit format is shown below.
<Response header>
Space
<Response Header>
A response header sometimes precedes the response
data. A space separates the data from the header.
For details, see page 3-4.
<Response Data>
Response data contains the content of the response.
If there are multiple sets of response data, they are
separated by commas (,). For details, see page 3-5.
Example
500.0E-03<RMT> :SAMPLE:INTERVAL MINIMUM<RMT>
Data
Header
3-2
<RMT>
Unit
,
<Response data>
Data
If there are multiple queries in a program message,
responses are made in the same order as the queries.
In most cases, a single query returns a single
response message unit, but there are a few queries
that return multiple units. The first response message
unit always corresponds to the first query, but the nth
response unit may not necessarily correspond to the
nth query. Therefore, if you want to make sure that
every response is retrieved, divide the program
messages into individual messages.
Precautions to Be Taken when Transferring
Messages
• If a program message that does not contain a query
is sent, the next program message can be sent at
any time.
• If a program message that contains a query is sent,
a response message must be received before the
next program message can be sent. If the next
program message is sent before the response
message is received in its entirety, an error occurs.
The response message that was not received is
discarded.
• If the controller tries to receive a response message
when there is none, an error occurs. If the
controller tries to receive a response message
before the transmission of the program message is
complete, an error occurs.
• If a program message containing multiple message
units is sent, and the message contains incomplete
units, the instrument will attempt to execute the
ones that are believed to be complete. However,
these attempts may not always be successful. In
addition, if the message contains queries, the
responses may not be returned.
Deadlock
The instrument can store in its buffer program and
response messages of length 1024 bytes or more (The
number of available bytes varies depending on the
operating conditions). When both the transmit and
receive buffers become full at the same time, the
instrument can no longer continue to operate. This
state is called a deadlock. In this case, operation can
be resumed by discarding the program message.
Deadlock will not occur if the program message
(including the <PMT>) is kept below 1024 bytes.
Furthermore, deadlock never occurs if a program
message does not contain a query.
IM 704510-17E
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