User`s manual

36 Using the Relay Multiplexer Modules Chapter 3
Scanning a Range of Switchbox Channels
• You can scan a range of channels of a switchbox consisting of single
or multiple multiplexer modules (see the “Comments” section for
scanning requirements of a switchbox).
• Scanning involves sequentially closing each channel on a range of
specified channels.
• During scanning, the relay which was previously closed opens before
the next relay closes.
Example: Making Voltage
Measurements by
Scanning
Figures 3-4, 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:
-- AT Tree Switch Terminals of each terminal module connect to each
other and to the multimeter in Figure 3-5; to connect the AT Tree
Switch Terminals to each other, use either the Analog Bus Cables;
Analog Bus (shown in Figure 2-2) or wire the terminals together
between each terminal modules.
-- E1300/E1301 Mainframe's "Trig Out" pulse synchronizes the
switchbox with the multimeter.
-- GPIB Bus trigger command advances the switchbox channel list.
-- Multimeter GPIB select code is 7 and primary address is 22.
-- Switchbox GPIB select code is 7, the GPIB primary address is 09,
and the GPIB secondary address is 14.
-- Computer is an HP Series 200/300 Computer with BASIC using
GPIB.
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
Switches while scanning;
automatically makes connection
to the Analog Bus.
60 OUTPUT 70914;"SCAN (@100:215)"
!Selects channel list. 100 selects
first channel of module #1;
215 selects last channel of
module #2.
70 OUTPUT 70914;"INIT"
!Starts scanning cycle.
80 FOR I=1 TO 32
!Start count loop.
90 ENTER 722;A
!Enter reading into variable A.
100 PRINT A
!Print reading in variable A.
110 TRIGGER 70914
!Trigger the switchbox to
advance the scan list.
120 NEXT I
!Increment count.
130 END