Sutter Instrument Lambda DG-4Plus/USB Operation Manual Download

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LAMBDA DG-4 & 5 PLUS/USB OPERATION MANUAL – REV.

4.1.5

Interface Modes

Using Input Lines Only:

The BUSY line used in the Lambda DG-4 was originally

implemented in an earlier version of the software that was written for the Lambda-10, a

much slower filter-switching device. Because of the DG-4’s superior filter switching speed, it
is not always necessary to attend the state of the BUSY line. In many experimental

applications, the Lambda DG-4 could be controlled entirely by using only the eight data input
lines. The extreme example of this approach would occur when all that is needed in your

application is to toggle between two FILTER NUMBERS. In this case, you could select
between FILTER NUMBERS 1 and 3 by holding the least significant bit value (data input

line 2) HIGH while toggling the next least significant bit value (data input line 3) LOW and
HIGH. The remaining data input lines (4-9) could simply be grounded to hold those bit
values LOW.

Using Input Lines with the BUSY Line:

The conditions that cause the BUSY line to be

asserted are noted in the previous paragraph. Reading the status of the BUSY line allows the
host computer to determine if the unit is ready to receive a command. A command sent while

the BUSY line is HIGH will not be executed until the BUSY line goes LOW. It is possible,
then, when using high performance software and hardware that the first of two commands

sent in succession could be “lost”. Monitoring the state of the BUSY line (Pin 8) can avoid
such losses and make time-consuming “time-outs” in the software unnecessary.

4.1.6

Controlling the Lambda DG-4 from a Computer’s Parallel (Printer) Port

The standard PC parallel port provided for printer control may be used to control the

Lambda DG-4. This, however, does not mean that instructions can be sent to the Lambda
DG-4 in the same manner that they are sent to a printer. A printer is designed to print at its

maximum rate, and if the computer generates output at a higher rate, the printer will store
the output in a buffer until the mechanism is ready. If the buffer becomes full, the printer

will indicate to the computer that it is not ready to accept more data. It follows that there is
not a tight time relationship between the output of a command from the computer and the
execution of that command by the printer.
The time relationship between output of data from the computer and response by the

Lambda DG-4, in contrast, must be very tight. Thus, it is understandable that the mode of
use of the parallel port will be somewhat different for a printer and the Lambda DG-4.
The details of the input and output signals were described previously. Now we will discuss
the way in which these signals may be used to control the Lambda DG-4 from a PC

compatible computer’s parallel port. This information is provided as a limited example and is
only intended to show the elements useful in controlling the Lambda DG-4. The user’s

individual requirements, hardware, and software will dictate the actual program steps to be
used. The approach in this example does involve direct control over the state of input and

output ports. The example programs have been run successfully on computers from several
manufacturers without encountering any difficulties. However, given the wide range of

hardware and software in use, it is impossible to anticipate all possible problems. Sutter
Instrument Company thus cannot be responsible for any damages that might result from use

of the example programs. The user should be particularly careful that the address used for
each of the various I/O ports is correct for the user’s system.
The parallel (printer) port is actually composed of three I/O ports at three consecutive
addresses. The first address corresponds to an 8 bit output port, the second to a 4 bit input