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Switchbox and Scanning Voltmeter Configurations
A VXIbus instrument is a module or group of modules which perform a
specified function. For the HP E1300/01 mainframe, the first module in an
instrument must have a logical address which is evenly divisible by 8 (16,
24, 112), and the rest of the modules in the instrument are numbered
consecutively. The instrument’s secondary address is the whole number
equal to the logical address divided by 8 (for a logical address of 16, 17,
18,…23, the secondary address is 02). For instrument definition in other
mainframes, see the mainframe manual. If an instrument consists of only
multiplexer modules, it is a switchbox configuration. If a multiplexer
module(s) is combined with a multimeter to form an instrument, that is a
scanning voltmeter configuration.
Switchbox A switchbox is a multiplexer module or group of multiplexer modules
which form a single instrument. A switchbox can be connected to a
multimeter which is a different VXIbus instrument, to an HP-IB
1
controlled
multimeter, or to a stand-alone multimeter. The switchbox and the
multimeter have different secondary addresses. Separate configuration
commands must be sent to the switchbox and to the multimeter. The
following program illustrates the different addresses and the configuration
commands required. The HP-IB interface select code is 7, and the
mainframe address is 09. The multiplexer has an instrument address of 24,
so its secondary address is 03. The multimeter is HP-IB controlled, and has
a primary address of 22.
10 OUTPUT 722;"TRIG EXT;DC 10" !Sets multimeter to external trigger
and to measure DC volts
20 OUTPUT 70903;"OUTP ON" !Enables "Trig Out" port
30 OUTPUT 70903;"TRIG:SOUR BUS" !Sets switchbox to receive Bus
triggers
40 OUTPUT 70903;"SCAN:MODE VOLT"!Set up switchbox for voltage
measurements
50 OUTPUT 70903;"SCAN:PORT ABUS"!Closes the appropriate tree
isolation switches while scanning,
automatically makes connection to
the analog bus and tree terminals.
60 OUTPUT 70903;"ARM:COUN 2" !Set for two cycles through the
scan list
70 OUTPUT 70903;"SCAN (@100;115)"!Selects the channel list. 100
selects first channel on card 1;
115 selects last channel on card 1
80 OUTPUT 70903;"INIT" !Close first channel to start
scanning cycle
90 FOR I = 0 TO 15 !Start count loop
100 ENTER 722;A !Enter reading into variable A
110 PRINT A !Print reading in variable A
14 Getting Started with the HP E1351A/53A Chapter 1
1 HP-IB is Hewlett-Packard’s implementation of IEEE Std 488.1-1978