Shutter Control Without Remote Control Commands Via The Dedicated Ttl Line; Remote Control Command Programming; Preparing The Command Byte; Encoding Filter Commands Into A Single Byte - Sutter Instrument LAMBDA 10-B Operation Manual

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5.5 Shutter Control without Remote Control Commands via the Dedicated TTL Line

The Special Commands shown above can be sent to the controller via the serial RS-232 port
or the USB (Universal Serial Bus) port. The protocol used to transmit these commands is as
Smart
described above in this chapter. The features of the Shutter can be used even without
proper software support of the various modes of operation. The fast, soft and neutral density
modes can be selected from the keypad. When so selected, open and close commands and the
TTL input will act in the selected fashion.
For a description of this alternative method of remote shutter control, please refer to the
REMOTE CONTROL: LOGIC LEVEL INPUT chapter later in this manual.

5.6 Remote Control Command Programming

This section describes some suggested tips and techniques when writing programs on the
remote control computer for communicating with the LAMBDA 10-B via either the serial RS-
232 port or the USB (Universal Serial Bus) port. The following paragraphs and the code
examples deal with remote control command programming in a general manner, abstracted
from telecommunications medium. The discussions and examples are applicable to either the
serial RS-232 port or the USB port. The programming specifics for either the serial or USB
ports are covered in the respective chapters, following this chapter. The discussions and
examples are also relatively platform independent. The code samples written in the C
programming language, for example, are written in a relatively primitive form, and thus
should be easily portable to any platform for which C support exists (Windows, UNIX, Linux,
Macintosh OS, etc.). Should another programming language be desired to implement the
examples, the gist of examples should be fairly easy to glean if they are viewed as pseudo code
– the examples should be easy to port to C++, Java, Pascal, BASIC, and other high level
languages, or even various forms of scripting languages.

5.6.1 Preparing the Command Byte

All remote control command codes for the LAMBDA 10-B require no more than one byte (8
bits) of storage for each command. If using a programming language that make a distinction
between unsigned and signed bytes, always select unsigned only. "Unsigned" means that
only positive numbers can be stored, whereas "signed" means that either positive or negative
values can be stored. An unsigned byte can hold 256 different positive values (0 through 255).
A signed byte can store only 128 different positive values (0 through 127, and 127 different
negative values (-1 through –127). In the C programming language, an unsigned byte type is
expressed as "unsigned char" followed by the name of the variable, such as:
unsigned char command_byte;
...where "command_byte" is the name, the programmer chooses to give the variable.

5.6.1.1 Encoding Filter Commands Into a Single Byte

Filter commands are encoded into specific bit groups of the command byte. As discussed
earlier in this chapter, and as shown in the table titled "Filter Command Structure", there
are actually three commands stored at the same time in the command byte. The filter wheel
selector is stored in Bit 7 (the most significant bit (MSB)) of the command byte, allowing 2
LAMBDA 10-B OPERATION MANUAL – REV. 1.20Q (20230227)