Keithley 6482, Справочное руководство

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6482-901-01 Rev. A / August 2012 Return to
Section Topics
C-7
Model 6482 Dual-Channel Picoammeter / Voltage Source Reference Manual Appendix C: IEEE-488 Bus Overview
Uniline commands
ATN, IFC, and REN are asserted only by the controller. SRQ is asserted by an external device.
EOI may be asserted either by the controller or other devices depending on the direction of data
transfer. The following is a description of each command. Each command is sent by setting the
corresponding bus line true.
REN (Remote Enable) : REN is sent to set up instruments on the bus for remote operation. When
REN is true, devices will be removed from the local mode. Depending on device configuration, all
front panel controls except the LOCAL key (if the device is so equipped) may be locked out when
REN is true. Generally, REN should be sent before attempting to program instruments over the
bus.
EOI (End or Identify) : EOI is used to positively identify the last byte in a multi-byte transfer
sequence, thus allowing data words of various lengths to be transmitted easily.
IFC (Interface Clear) : IFC is used to clear the interface and return all devices to the talker and
listener idle states.
ATN (Attention) : The controller sends ATN while transmitting addresses or multiline commands.
SRQ (Service Request) : SRQ is asserted by a device when it requires service from a
controller.
Universal multiline commands
Universal commands are those multiline commands that require no addressing. All devices
equipped to implement such commands will do so simultaneously when the commands are
transmitted. As with all multiline commands, these commands are transmitted with ATN true.
Table C-1
IEEE-488 bus command summary
Command
type
Command
State of
ATN line Comments
Uniline
Multiline
Universal
Addressed
Unaddressed
Common
SCPI
REN (Remote Enable)
EOI (End Or Identify)
IFC (Interface Clear)
ATN (Attention)
SRQ (Service Request)
LLO (Local Lockout)
DCL (Device Clear)
SPE (Serial Poll Enable)
SPD (Serial Poll Disable)
SDC (Selective Device
Clear)
GTL (Go To Local)
UNL (Unlisten)
UNT (Untalk)
–
–
X
X
X
Low
X
Low
Low
Low
Low
Low
Low
Low
Low
High
High
Set up devices for remote operation.
Marks end of transmission.
Clears interface.
Defines data bus contents.
Controlled by external device.
Locks out local operation.
Returns device to default conditions.
Enables serial polling.
Disables serial polling.
Returns instrument to default
conditions.
Returns device to local.
Removes all listeners from the bus.
Removes any talkers from the bus.
Programs IEEE-488.2 compatible
instruments for common operations.
Programs SCPI compatible
instruments for particular operations.