Bus Commands; Uniline Commands - Keithley 776 Instruction Manual

IEEE-488 Operntion
1. Press the 2nd push-button once then press the ADR
push-button (second function to SLOPE). The display
will be modified to display the following:
IE Adr x
Where s may be any number from 0 to 30
2. Press the VERNIER fi or u push-buttons the select a
new GPIB primav address.
3. To store the newly selected primary address depress
ENT (second function to STO). The instrument a-ill then
resume normal operation,
4-8. Bus Commands
Uniline commands are sent by setting the associated bus
line to low. The ATN. IFC. and REN commands are
asserted only by the system controller. The SRQ com-
mand is sent by an external device. The EOI command
may be sent by either the controlleroran external device
depending on the direction of data transfer. The follow-
ing is description of each command.
While the hardware aspect of the bus is essential. the
REN
(Remote Enable) - The rcmotc cnablc command is
interface would be essentially worthless without appro- sent to the Model 776 by lhe controller to set the instru-
priate commands to control the communications be- ment up for remote operation Generally. this should bc
tween the various instruments on the bus. This para- done before attempting to program the instrument over
graph briefly describes the purpose of the bus com- the bus. The Model 776 will indicate that it is in the
mands. which are grouped into the following three cate- remote mode by illuminating its front panel REM indi-
cator.
1. Uniline commands: Sent by setting the associated bus
line low.
2. Multiline commands: General bus commands which
arc sent over the data lines with the ATN lint low (true).
3. Device-dependent commands: Special commands
that depend on dcvicc configuration: sent oycr the data
lines with ATN high (false).
4-8-l Uniline Commands
r
COMMAND COMMAND STATE OF COMMENTS
TYPE ATN LINE(*)
Uniline
REN
X
Set up for remote operation
EOI X Sent by setting EOI Ion
IFC
X Clears Interface
ATN
LO\\ Dcfincs data bus contents
SRQ
X~ Controlled by~~external de\,icc
Multiline Universal
LLO
Lon Locks out front panel controls
DCL
LO\\ Returns device to default conditions
SPE
Loa Enable serial polling
SPD
LOI\ Disables serial polling Addressed
SDC
Lou Returns unit to default condition
GTL
LO\%
Returns to local control
~~.~~-. -.~.~-~GET.~ .,,!m
Tiggq device. for mading
Unaddress UNL
Len Removes all listeners from bus
UNT LO\\
Removes all talkers from bus
Device- Dependent(**)
High
Programs Model 60.10 for various modes.
(*I X = Don't Care. l**) See paragraph .l-9 for complete description
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