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-IB1controlled 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

30OUTPUT 70903;"TRIG:SOUR BUS" !Sets switchbox to receive Bus triggers

40OUTPUT 70903;"SCAN:MODE VOLT"!Set up switchbox for voltage measurements

50OUTPUT 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

70OUTPUT 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

1HP-IB is Hewlett-Packard’s implementation of IEEE Std 488.1-1978

14 Getting Started with the HP E1351A/53A

Chapter 1