5-2
IM WT310E-17EN
5.1 Messages
Response Message Unit Syntax
The response message unit syntax is as follows:
,
<Response header>
<Response data>
Space
<Response Header>
A response header sometimes precedes the response
data. Separate the data from the header with a space.
For details, see page 5-5.
<Response Data>
Response data contains the content of the response. If
there are multiple sets of response data, separate each
set with a comma. For details, see page 5-5.
Example
100.00E-03<RMT> :INPUT:MODE RMS<RMT>
Header
Data
Data
If there are multiple queries in a program message,
responses are returned in the same order that the
queries were received in. 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 Sending and
Receiving Messages
• If the controller sends a program message that does
not contain a query, the controller can send the next
program message at any time.
• If the controller sends a program message that
contains a query, the controller must finish receiving
the response message before it can send the next
program message. If the controller sends the next
program message before receiving the response
message in its entirety, an error will occur. A
response message that is not received in its entirety
will be discarded.
• If the controller tries to receive a response message
when there is none, an error will occur. If the
controller tries to receive a response message
before the transmission of the program message is
complete, an error will occur.
• If the controller sends a program message
containing multiple message units, but the message
contains incomplete units, this instrument will try to
execute the ones that are believed to be complete.
However, these attempts may not always be
successful. In addition, if such a message contains
queries, this instrument may not necessary return
responses.
Deadlock
This instrument can store at least 1024 bytes of
messages in its transmit and receive buffers (the
number of available bytes varies depending on the
operating conditions). If both the transmit and receive
buffers become full at the same time, this instrument
will no longer be able to operate. This condition is
called a deadlock. If this happens, you can resume
operation by discarding response messages.
Deadlock will not occur if the program message
(including the <PMT>) is kept below 1024 bytes.
Program messages that do not contain queries never
cause deadlocks.
