Interface Modes; Controlling The Lambda Dg-4/5 From A Computer's Parallel (Printer) Port - Sutter Instrument Lambda DG-4 Operation Manual

the BUSY line is set HIGH. Thus, checking the status of the BUSY line within about 100
microseconds of changing the input lines may give a misleading result.

4.1.5 Interface Modes

Using Input Lines Only:
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-4/5'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-4/5 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:
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-4/5 from a Computer's Parallel (Printer) Port

The standard PC parallel port provided for printer control may be used to control the
Lambda DG-4/5. This, however, does not mean that instructions can be sent to the Lambda
DG-4/5 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-4/5, 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-4/5.
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-4/5 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-4/5. 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
The BUSY line used in the Lambda DG-4/5 was originally
The conditions that cause the BUSY line to be
LAMBDA DG-4 & DG-5 OPERATION MANUAL – REV. 3.05C (20150414)
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