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Scan Clear Switch
At the back of the 53A-334 Card (see Figure 334-1) is a 1-section rocker switch, the Scan Clear
switch, that determines i f the card is to open all its channels when a channel is closed on
another 53/63 Series System scanner card.
Rocker Position R e s u l t s
Cl
A closed channel on this 53A-334 Card is opened when a channel is
closed on another 53/63 Series System scanner card. Closing a channel
on this card sends a scan clear pulse to all other scanner cards.
C2
C
l
o
s
i
n
g
channels on other scanner cards has no effect on this 53A-334
Card. When a channel is closed on this card, a scan clear pulse is not
sent to other scanner cards.
Speed Select Switch
At the back of the 53A-334 Card is a 2-position rocker switch, the Select switch (see Figure
334-1). This switch selects the switching rate for this card: 150 channels per second (cps) or 350
cps. I t also determines if the scanner-card's slow/fast status is sent to the slow/fast line on the
53/63 System Backplane and to the front edge of the 53A-334 Card.
The purpose of the slow/fast line is to slow down operation of the card when used in a system
with slower scanners, thus preventing the card from closing a relay before a relay on another
slower card has opened. ( To locate the slow/fast line on the Backplane and on the front edge
connector, refer to Appendix B and to the Service Manual schematic.)
Rocker Position R e s u l t s
Cl, C3
I
f
the previous channel closed is on this or another high- speed scanner
card, then closing a channel on this 53A-334 Card occurs immediately.
Otherwise channels switch at 150 cps. O t h e r high-speed cards will
receive status from this 53A-334 Card. N O T E : The Scan Clear Switch
must, be in the Cl position.
C2, C3
I
f
the previous channel closed was on this 53A-334 Card, then closing
a channel on this card occurs immediately. Otherwise channels switch
at 150 cps. O t h e r high-speed cards will not receive slow/fast status
from this card.
NOTE:
T h e Scan Clear switch may be in either Cl or
C2 position.
Cl, C4 C h a n n e l s switch at 150 cps. Other high-speed cards will receive slow
status from this card.
NOTE:
The Scan Clear switch must be in the Cl
position.
C2, C4 C h a n n e l s on this card will switch at 150 cps. Other high- speed cards
will not receive fast or slow status from this card.
N O T E :
T h e Scan
Clear switch may be in either CI or C2 position.
NOTE: F o r most applications, the Speed Select switch should be set to position CI, C3, and
the Scan Clear switch must be in the Cl position.
334 - 5