User manual

as the room control button is pressed. The two relays
each have two sets of contacts, one normally open,
and one normally closed. Therefore, two devices can
each have up to four actions associated with them—
for instance, on/off and up/down. For example, the
two contacts (on one relay) could be used to lower
the projector and turn off room lights.
Figure 1 shows a schematic of the relays used on the
System 7SC.
Each contact is capable of handling 24 volts and up
to one amp. The action of relay contacts on the
System 7SC can be changed, depending on the
requirements of the third party control device, to
operate in one of two ways:
1. Latching— The relay changes position when the
button is pressed and remains in that position
until the button is pressed again.
2. Momentary— When the button is pressed the
relay changes position (makes contact) for a short
period. This period is adjustable.
Once the relay operation is programmed, the relays
can be used to control external devices. As mentioned
above, third party controllers can be connected to the
relay contacts to allow remote control.
18 ExtroNews 12.1 January/February 2001
TECH CORNER
The System 7SC provides switching, projector
control, and room control: everything needed for a
single room application. Room control is a feature of
the System 7SC that allows equipment such as a
projector lift, screen mechanism (to raise/lower a
screen), lights, or other electrical devices to be
controlled by the System 7SC. The user can control
these devices directly from the System 7SC, or remotely
with an IR remote, or from SCP control pads located
throughout a room.
Control Relays
To control external room devices the System 7SC
uses two built-in relays. These relays in turn operate
third party control devices which actually control the
room equipment. Each relay can be operated
independently. The relays open and close, or make
momentary contact (depending on how they're set up)
Using the System 7SC for Room Control
by Roger McCarten, Product Development Manager
Normally closed Normally closed
Normally open Normally open
System 7SC
Relay ports
ABC
RELAY 2RELAY 1
DEABCDE
To / from
room control
equipment
Normally closed
A
Normally closed
B
Normally open
C
Normally open
D
Not used
E
System 7SC
IR 701 Remote
SYSTEM 7SC
COMPUTERS-VIDEO
LR
VIDEO AUDIO
INPUT 7
CONTROL
IRDISPLAY
VOLUME
RX LEARN
TX
RX
ADJUST
DETAIL
NEXT
CONT
MENU
BRIGHTTINTCOLOR
DISP
PWR
DISP
MUTE
MODE
ROOM
1
ROOM
2
1234567
CONTROL
DISP
PWR
MUTE
On/Off
MODE
Lights
On/Off
Screen
Up/Dwn
VCR DVD LT PC DOC MAC VC
Figure 2. Functions on the System 7SC can be
controlled by an IR remote.
Figure 1. Pressing room
control buttons opens and
closes relay ports.
E
xtron recently introduced the System 7SC switcher. The System 7SC can be thought
of as an all-in-one switching and control solution for conference rooms, classrooms,
meeting rooms—any small to medium-sized application where the budget is limited.