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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 if the card is to open all its channels when a channel is closed on
another 53/63 Series System scanner card.
Rocker Position Results
Cl Aclosed 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 Closing 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. It 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 Results
Cl, C3 If 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. Other high-speed cards will
receive status from this 53A-334 Card. NOTE: The Scan Clear Switch
must, be in the Cl position.
C2, C3 If the previous channel closed was on this 53A-334 Card, then closing
achannel on this card occurs immediately. Otherwise channels switch
at 150 cps. Other high-speed cards will not receive slow/fast status
from this card. NOTE: The Scan Clear switch may be in either Cl or
C2 position.
Cl, C4 Channels 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 Channels on this card will switch at 150 cps. Other high- speed cards
will not receive fast or slow status from this card. NOTE: The Scan
Clear switch may be in either CI or C2 position.
NOTE: For most applications, the Speed Select switch should be set to position CI, C3, and
the Scan Clear switch must be in the Cl position.
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