Instruction manual

61
- when ATN line is false (high), the bus is in data mode and data bytes
are transferred over the interface. These bytes may be SCPI
commands sent by the addressed Talker to the addressed Listeners.
or a response sent by a previously interrogated Listener (eg: response
to an interogative command). The interrogated device must be
addressed as a Talker in order to be able to transmit the response.
Only addressed Listener (s) will acknowledge them.
SendingCcommands over GPIB Remote Interface
GPIB byte commands are sent together with address bytes while ATN line is
low.
SCPI commands are sent after address bytes are sent. The power supply must
be addressed as Listener. While sending address bytes, ATN line is low. While
sending SCPI commands, ATN line is high.
If the SCPI command is interrogative, after sending the command, the Active
Controller must address the power supply as a Talker. Then ATN line goes
high and the power supply can send the answer to the Active Controller.
Command terminators
When GPIB interface is selected, a command string sent to the power supply
may terminate in different ways, depending on the GPIB interface card.
§
§ Line feed character (0a h) combined with EOI line low
§
§ Line feed character (0a h) and carriage return character (0d h)
combined with EOI line low
§
§ EOI line low
§
§ For multiple commands sent in a single message, command
separator is semicolon character (03b h).
When multiple commands are sent in the same message, EOI line
goes low while the last character of the message is sent (it may be
line feed character, carriage return character or the last character
of the last command).
When addressed as a Talker, the power supply use the following termination
scheme: line feed character combined with EOI line low.
When Status Byte is transmitted by the power supply (part of Serial Poll
Procedure), EOI line does not go low.