Card Connections and Installation
2-9
The logic device is a demultiplexer (DMUX). The binary
pattern (value) seen at the input of the DMUX (lines A, B and
C) determines which DMUX output line (Y0 through Y7) is
selected (pulled low). For example, with channels 25, 26 and
27 off (open), lines A, B and C are high. The binary 7 at the
DMUX input (A = 1, B = 1 and C = 1) selects (pulls low) out-
put Y7. If channel 26 is turned on (closed), line B goes low.
The binary 5 seen at the DMUX input (1, 0, 1) selects (pulls
low) Y5.
NOTE
With jumper W105 removed, all of the
above output connection schemes could be
used at the same time (assuming that cur-
rent sink limits are not exceeded). Remov-
ing jumper W105 allows you to use two
different external voltage sources (V
EXT1
and V
EXT2
).
2.10 Typical input connection scheme
Figure 2-13 shows a digital input connection scheme to mon-
itor the state of micro-switches. With a switch open, the cor-
responding input channel is pulled high by the internal pull-
up resistor. As a result, the input channel is on (closed).
When a switch is closed, the corresponding input channel is
pulled low to ground. As a result, the input channel is off
(open).
2.11 Models 7020-D and 7020-DT
The Models 7020-D and 7020-DT are alternate configura
tions of the Model 7020 Digital I/O Interface Card. The
Model 7020 consists of a scanner card and a connector card
in a sandwich. The configurations are as foll ws:
• Model 7020 — Scanner card and mass-terminated card
with 96-pin male DIN connector.
• Model 7020-D — Scanner card and mass-terminated
card/cable with 50-pin male and female D-Sub
connectors.
• Model 7020-DT — Spare mass-terminated card/cable
with 50-pin male and female D-Sub connectors.
This section describes additional information for the Models
7020-D and 7020-DT
Internal connections
The two PC-boards that plug together are secured by a 4-40
screw (see Figure 2-14).
IN 2
IN 1
MICRO-
SWITCHES
7020
IN 3
GND
Figure 2-13
Digital input, monitoring micro-switches
4-40 x
¼
” PPHSEM
(5 IN-LBS)
7020-010,
SCANNER BOARD
7020-019,
MASS TERM BOARD
WA
RNIN
G
Figure 2-14
Mating the PC-boards