Sutter Instrument Lambda 421, Operation Manual

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LAMBDA 421 OPERATION MANUAL – REV. 1.00N (20170623)
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all of the LEDs. When you select a particular filter value you will therefore activate the LED
that corresponds to that filter value but you will also set the voltage for the current control
to the value that corresponds to the DAC setting set for that filter value. We will likely store
DAC values for each filter value according to a scheme similar to the DG-4, but this can
easily be changed. Thus, LEDs 1, 2, and 3 have four different programmable current levels
selected by calling the correct filter value. LED 4 only has three separate values and there is
only one value for OFF: Filter 0.
When operating the Lambda under full control of the DG-4 interface you would set each
channel to TTL control and EXT. current control using the front panel switches. The current
control knobs can be used to attenuate the output of any channel, if desired. The control of
the LEDs then is entirely from the DG-4 interface. The connections for the DG-4 interface
are all available on the back panel.
Figure 3-2. Rear panel of the Lambda 421.
The USB interface to a control computer is the default method of control. In most cases the
USB port will be used in the virtual com port mode which enables this port to support
software that was developed for use with serial port control. There is also a true RS232 serial
port, but this cannot be used at the same time as the USB port. Selecting which of the two
ports is active will be discussed elsewhere. The other option for full control is the parallel
port. While this input provides very short latency few systems offer the full 8 bits needed to
input all types of commands. This port is not fully bi-directional, so it does not allow reading
settings back to the computer. The most common use of the parallel port is for rapid selection
of the active channels via individual TTL signals, as will be discussed elsewhere.
FILTER VALUE OUTPUT RJ-45 Receptacle