G-4
GPIB 488.1 Protocol
NRFD hold-off
*OPC, *OPC?, and *WAI are still functional but are not needed for the 488.1 protocol.
When sending commands, the GPIB is automatically held off when it detects a terminator. The
hold-off is released when all the commands have
fi
nished executing, or if there is some parser
or command error. An exception is an initiate command, which releases the hold-off immedi-
ately and does not wait for all of the readings to be acquired. This immediate release of bus
hold-off is done to support GET, SDC, IFC, *TRG, *RCL, *RST, SYSTem:PRESet and
ABORt during data acquisition.
NDAC hold-off
NDAC is included with the GPIB 488.1 protocol mode to allow a single instrument to hold
off all others on the bus until it is
fi
nished executing a command. The following command con-
trols NDAC hold-off:
SYSTem:MEP:HOLDoff ON | OFF
The default is OFF, but NRFD hold-off will still be enabled and will prevent an instrument
from accepting further commands. See Figure G-1 for the complete IEEE-488 handshake
sequence.
DATA
DAV
SOURCE
SOURCE
VALID
ALL READY
ACCEPTOR
NRFD
NDAC
ALL ACCEPTED
ACCEPTOR
Figure G-1
IEEE-488 handshake
sequence
Summary of Contents for 6430
Page 26: ......
Page 32: ......
Page 78: ...2 14 Connections ...
Page 98: ...3 20 Basic Source Measure Operation ...
Page 138: ...5 30 Source Measure Concepts ...
Page 156: ...6 18 Range Digits Speed and Filters ...
Page 168: ...7 12 Relative and Math ...
Page 176: ...8 8 Data Store ...
Page 202: ...9 26 Sweep Operation ...
Page 248: ...11 22 Limit Testing ...
Page 310: ...16 6 SCPI Signal Oriented Measurement Commands ...
Page 418: ...17 108 SCPI Command Reference ...
Page 450: ...18 32 Performance Verification ...
Page 477: ...A Specifications ...
Page 489: ...B StatusandErrorMessages ...
Page 498: ...B 10 Status and Error Messages ...
Page 499: ...C DataFlow ...
Page 503: ...D IEEE 488BusOverview ...
Page 518: ...D 16 IEEE 488 Bus Overview ...
Page 519: ...E IEEE 488andSCPI ConformanceInformation ...
Page 523: ...F MeasurementConsiderations ...
Page 539: ...G GPIB488 1Protocol ...
Page 557: ......