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Scanning a Range of Switchbox Channels
You can scan a range of channels of a switchbox consisting of single or
multiple multiplexer modules. Scanning involves sequentially closing each
channel on a range of specified channels. The selected
TRIGger mode
determines when the channel closure will advance. During scanning, the
FET which was previously closed opens before the next FET closes.
You can use any of the
TRIGger modes to advance the channel list.
TRIGger:SOURce EXTernal requires an external trigger source to be connected
to the HP E1300/1301 Mainframe "Event In" port. For computer controlled or
HP-IB triggering (
TRIGger or *TRG) use TRIGger:SOURce BUS. The
OUTput ON command enables the mainframe’s "Trig Out" port to synchronize
multimeters when not in the
TRIGger:SOURce DBUS | IMM modes.
For the fastest scan rate (up to 100 K switches/sec.) use
TRIGger:SOURce
DBUS
. Use a custom cable (see “Digital Bus and Triggering” on page 15)
to connect the multimeter handshake lines (Voltmeter Complete and
External Trigger) to the multiplexer digital bus.
Example: Making
Voltage Measurements
by Scanning
Figures 3-4 and 3-5, and the following commands, show how to make
voltage measurements by performing a single scanning cycle of all channels
on two multiplexer modules in a single switchbox. In the example, the:
• A Tree Terminals of each terminal module connect to each other and
to the multimeter in Figure 3-5. To connect the A tree terminals to
each other, use either the analog bus cables (shown in Figures 2-10
and 2-11) or wire the terminals together between the terminal
modules.
• HP-IB Bus trigger command advances the switchbox channel list.
• HP E1300A/E1301A Mainframe’s "Trig Out" pulse synchronizes the
switchbox with the multimeter.
• Multimeter HP-IB select code is 7 and primary address is 22.
• Switchbox HP-IB select code is 7, the HP-IB primary address is 09,
and the HP-IB secondary address is 14.
• Computer is an HP Series 200/300 Computer with HP BASIC using
HP-IB.
Enter and Execute:
10 OUTPUT 722;"TRIG EXT;DC 10" !Sets multimeter to external
triggers and to measure dc volts
20 OUTPUT 70914;"OUTP ON" !Enables "Trig Out" port
30 OUTPUT 70914;"TRIG:SOUR BUS" !Sets switchbox to receive bus
triggers
40 OUTPUT 70914;"SCAN:MODE VOLT"!Setup switchbox to measure
voltage
50 OUTPUT 70914;"SCAN:PORT ABUS"!Closes the appropriate tree
isolation switches while scanning;
automatically makes connection to
the analog bus and tree terminals.
36 Using the HP E1351A/53A FET Multiplexer Modules Chapter 3