When the sync board is enabled, the sync pulse is also pro-
vided to the local sync output (P5 on the sync board; figure
4.1). The master enclosure’s local sync output can be used to
drive the local sync inputs of several slave enclosures, or they
may be daisy-chained by connecting the master enclosure to
the local sync input (P1 on the sync board; figures 4.1 and 4.2)
of the next slave enclosure, and so on (see figures 4.1 and 4.2).
External Control of Board Ensemble (2 rack unit enclosures only)
You can manually set who or what controls the sync board by
setting the J1 jumper on the sync board (see figure 4.1). Pin 1
of the J1 header is processor enable control. Pin 2 is con-
nected to the internal enable circuitry and is pulled to ground
by a resistor. Pin 3 is tied up to +5V. Normal operation has
pins 1 and 2 connected with a jumper, which allows the CPU
to control the board. Leaving the jumper off the J1 header
disables the board. You can manually control the board by at-
taching a normally open switch to pins 2 and 3 of the J1
header. Or, you can digitally control the sync board from an
external controller by connecting a TTL signal to pin 2, in
which case, a 1 enables the board and a 0 disables it.
4.1.1
Parts of the Sync Board
The following is a description of the important and adjustable
parts of the sync board. They fall into two categories, Exter-
nal Connections and On Board Jumper Settings.
4.1.1.1
External Connections
Five external BNC-type connectors (three connectors for 3
rack unit and 4 rack unit enclosures) are attached along the
left side of the board, as seen in figures 4.1 and 4.2.
Each of the BNC-type connectors serves a different function.
A description of each connector and what each one is used for
follows.
P1 – Input (Local Sync); 2, 3, and 4 rack unit enclosures
The local sync input is designed to be connected, by a cable, to
the local sync output of another sync board. The local sync in-
put allows the enclosure to be switched on command from the
master enclosure. The enclosure performs a switch immedi-
ately when it receives an active low TTL-level signal. The
signal is echoed out the local sync output connector. A master
enclosure can sequence the switching of an entire distribution
matrix by either driving all the local sync inputs of the slave
enclosures in parallel, or connecting them input to output in a
daisy-chain fashion.
4-3
Options
