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5.1 Messages
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 5-4.
<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 5-5.
Example
100.00E-03<RMT>
:DISPLAY:MODE WAVE<RMT>
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 n
response unit may not necessarily correspond to the
th
n
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.
5-2
,
<Response data>
Header
Data
th
• If a program message containing multiple message
units is sent, and the message contains incomplete
units, the instrument attempts 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 its communication
operation. 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 760301-17E
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