2.2 Introduction
2 – 3
2.2
Introduction
When an SR475 or SR476 is operated through an SRS shutter con-
troller such as the SR470 Shutter Controller or the SR474 Four-
Channel Shutter Driver, that instrument normally signals the shutter
head to open or close through the shutter head’s logic-level control
input.
The SR475 and SR476 also support serial communication and may
be remotely programmed via this interface.
Any host computer interfaced to an SR475 or SR476 shutter head
through a shutter controller may use that controller to relay (pass
through) serial commands to the shutter head. This allows the SR475
or SR476 to be controlled remotely through the controller’s inter-
faces, which may include Ethernet, RS-232, and
/
or GPIB.
The SR475 and SR476 can also be operated as stand-alone devices
without an SRS controller. See
§
1.7.1.1 for details.
2.2.1
Control modes
By default, the SR475 and SR476 follow the state dictated by the
logic-level control input (
§
1.7.1.2). However, this behavior can be
overriden through the use of the serial interface.
Executing any remote command that changes the position of the
shutter blade will force the shutter into
logic level lockout mode
,
where it will no longer respond to the logic-level control signal. Note
that SRS shutter controllers, such as the SR470 Shutter Controller and
the SR474 Four-Channel Shutter Driver, normally control the state
of the shutter through the logic-level input, but cannot do so when
that interface is locked out. Hence, care should be exercised when
directly commanding the shutter state over the serial interface.
Logic level and remote interface control of the blade position can be
separately enabled or disabled through the remote interface.
Also keep in mind that settings and modes of the SR475 and SR476
only exist in volatile memory, and at power-on the instrument always
returns to its default state.
2.2.2
Timing considerations
While it is possible to open and close the SR475 and SR476 Laser
Shutters through direct commands over its serial interface, these op-
erations are executed with significantly lower timing precision than
control through the logic-level input. Whenever timing is important,
serial control of the shutter position should be avoided.
SR475 and SR476 Laser Shutters
