IEEE-488 Reference
3-26
Response messages
A response message is the message sent by the instrument to the computer in response to a query
command program message.
1.
Sending a response message:
After sending a query command, the response message is
placed in the Output Queue. When the Model 6517A is then addressed to talk, the response
message is sent from the Output Queue to the computer.
2. Multiple response messages:
GPIB —
If you send more than one query command in the same program message (see
Multiple command messages), the multiple response message for all the queries is sent to
the computer when the Model 6517A is addressed to talk. The responses are sent in the or-
der that the query commands were sent and are separated by semicolons (;). Items within
the same query are separated by commas (,). The following example shows the response
message for a program message that contains four single item query commands:
0; 1; 1; 0
RS-232 Interface —
Instead of commas, a <CR>, <LF> will separate each response from
multiple queries in the same program message.
3.
Response Message Terminator (RMT):
Each response message is terminated with an LF
(line feed) and EOI (end or identify). The following example shows how a multiple re-
sponse message is terminated:
0; 1; 1; 0 <RMT>
Message exchange protocol
The message exchange protocol can be summarized by the two following rules:
Rule 1. You must always tell the Model 6517A what to send to the computer.
The following two steps must always be performed, in this order, to send information from the
instrument to the computer:
1. Send the appropriate query command(s) in a program message.
2. Address the Model 6517A to talk.
Rule 2. The complete response message must be received by the computer before another
program message can be sent to the Model 6517A.
