Keithley 7022, Instruction Manual

Page: 29 / 107

Matrix Configuration
2-9
Partial matrix implementation
A fully implemented matrix provides a relay at each poten-
tial crosspoint. For example, a fully implemented 10
×
12
matrix utilizing four 5
×
6 cards contains 120 crosspoints. A
partially implemented 10
×
12 matrix would contain fewer
crosspoints.
An example of a partially implemented 10
×
12 matrix is
shown in Figure 2-12. The partial matrix is still considered
10
×
12 but contains only 90 crosspoints using three Model
7022 cards installed in two Model 7001/7002 mainframes.
Matrix card #1 (7022 #1) installed in one of the slots of the
first mainframe (7001/7002 #1) provides a 5
×
6 matrix. The
other slot of the first mainframe should be left empty. If
another switching card is left in that slot, it must be iso-
lated from the analog backplane (i.e., backplane jumpers
removed). The two cards (7022 #2 and #3) installed in
the second mainframe (7001/7002 #2) are configured as a
10
×
6 matrix as explained in the wide matrix expansion
(10
×
6) paragraph. Remember that the rows of card #2 must
be isolated from the rows of card #3. This is accomplished by
removing the jumpers on one of the two cards. Finally, the
partially implemented 10
×
12 matrix is realized by exter-
nally hard-wiring the rows of card #1 to the rows of card #2.
An obvious advantage of a partial matrix is that fewer cards
are needed. Another reason to use a partial matrix is to keep
specific devices from being connected directly to other
devices. For example, a source connected to rows F, G, H, I,
or J (Figure 2-12) cannot be connected to a column of Model
7022 #1 with one “accidental” crosspoint closure. Three spe-
cific crosspoints must be closed in order to route the source
signal to a column of card #1.
A
B
C
D
Rows
1
Columns
7022 #1
7001/7002 #1
External
Row
Jumpers
7
Columns
7022 #2
12
7001/7002 #2
7022 #3
F
G
H
I
Rows
6
E
J
Figure 2-12
Partial matrix expansion (10
×
12)
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