1 – 8
Getting Started
an auxiliary I
/
O port, a chassis-grounded binding post, three remote
interfaces, configuration DIP switches, and the power entry module.
The SR474 serial number and ethernet MAC address are printed on
a label located on the back side.
1.3.1
Power entry
The power entry module is located on the upper left side of the rear
panel and contains an integrated power switch.
The universal input power supply of the SR474 accommodates any
voltage in the range 90 VAC to 260 VAC, with a frequency in the range
47 Hz to 63 Hz.
The SR474 has a detachable, three-wire power cord for connection
to the power source and to a protective ground. The exposed metal
parts of the instrument are connected to the outlet ground to protect
against electrical shock. Always use an outlet which has a properly
connected protective ground.
1.3.2
Chassis ground
This binding post is connected to the SR474 chassis and to earth
ground.
1.3.3
TTL Inputs
The primary control inputs for the SR474 Four Channel Shutter
Driver are the four rear-panel BNC inputs corresponding to the four
shutter channels.
Each channel’s input, labeled “TTL In,” accepts an externally gen-
erated logic-level input signal that controls the state of a shutter
connected to that channel, when the channel is both enabled and
set to the
TTL
source mode. The inputs are internally pulled up to
+
3.3 VDC through 100 k
Ω
and are compatible with
+
5 VDC (TTL)
input signals.
The inputs are
active low
. A signal that is unasserted, i.e., logically
high or open (disconnected), commands the associated shutter to
its
Normal
state. An input signal that is asserted, i.e., pulled low,
commands an a
ff
ected shutter to its
normal
state.
Note: The shield of each input BNC is connected to earth ground.
1.3.4
Shutter connectors
The SR474 has four output connectors, each of which provides power
and interface connections for an external SR470 Series Laser Shut-
SR474 Four Channel Shutter Driver
