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5790A
Operators Manual
5-42. Bus Communication Overview
Communication between the controller and the 5790A takes place using commands
established by IEEE-488 standards and commands specifically related to the 5790A. The
commands listed in Section 6 are all the remote commands, both common and device-
dependent. Definitions of the different types of messages used on the IEEE-488 bus
follow.
Uinterface
Function
SH1
AH1
T6
TE0
L4
LE0
SR1
RL1
PP0
DC1
DT1
C0
5-43. Device-Dependent Commands
Device-dependent commands are messages used to transfer information directly between
the 5790A and the IEEE-488 controller. Some commands cause an action to take place in
the 5790A. Others, called queries in the IEEE standards, ask for information, and always
generate a response message from the instrument. While message format is governed by
IEEE-488 standards, messages themselves can be unique to the 5790A. For example,
device-dependent commands are used to set the output mode and amplitude, and to
switch from standby to operate.
5-44. Common Commands
IEEE standard 488.2 defines common commands, which are used for functions common
to most bus devices. Examples include the command for resetting a device (*RST) and
the query for device identification (*IDN?). Common commands and queries can be
identified easily because they all begin with an asterisk (*).
5-45. Interface Messages
IEEE standards define interface messages, which manage the interface system. Some of
the interface messages have their own control lines, and others are sent over the data lines
by first asserting the control line ATN (Attention). An important thing to note about
interface messages is that unlike device-dependent and common commands, interface
messages are not sent literally (in a direct way). For example, when you send a device-
dependent query to the 5790A, the controller automatically sends the interface message
MTA (My Talk Address).
5-22
Table 5-5. IEEE-488 Interface Function Subsets Supported
Complete source handshake capability
Complete acceptor handshake capability
Basic talker, serial poll, no talk-only mode, Unaddress if MLA
No extended talker capability
Basic listener operation, no listen-only mode, Unaddress if MTA
No extended listener capabilities
Full service request capability, with bit-maskable SRQ
Full remote/local capability, including local lockout
No parallel poll capability
Device clear capability
Device trigger capability
No bus control capability
Description
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