Sutter Instrument Lambda DG-4Plus/USB, Руководство по эксплуатации

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LAMBDA DG-4 & 5 PLUS/USB OPERATION MANUAL – REV.
1.01B3
(
20190607
)
36
Table 2. USB-VCP interface serial port settings.
Property Setting
Data (“Baud”) Rate (bits per second (bps)) 128000
Data Bits 8
Stop Bits 1
Parity None
Flow Control None
The settings shown in the above table can be set in the device driver’s properties (via the
Device Manager if in Windows) and/or programmatically in your application.
NOTE: For compatibility with many existing software packages designed to control the DG-
4/5 over a serial interface, it is recommended that the data rate shown in the previous table
be changed to 9600 bps (“baud”) (via the DG-4/5Plus/USB’s keypad/display) if using the VCP
interface instead of the serial 9-pin interface..
Handshaking: Command sequences do not have terminators. If a command sequence just
sent to the controller is determined to be valid, the entire sequence is immediately echoed
back to the computer. All commands return an ASCII CR (Carriage Return; 13 decimal, 0D
hexadecimal) to indicate that the task associated with the command has completed. When
the Lambda DG-4/5 Plus/USB completes the task associated with a command, it sends ASCII
CR back to the host computer indicating that it is ready to receive a new command. If a
command returns data, the last byte returned is the task-completed indicator.
Commands: Each command sequence consists of at least one byte, the first of which is the
“command byte”. Those commands that have parameters or arguments require a sequence of
bytes that follow the command byte. No delimiters are used between command sequence
arguments. Every command and command sequence ends with a terminator byte containing
an ASCII CR (13 decimal, 0D hexadecimal). Although most command bytes can be expressed
as ASCII displayable/printable characters, the rest of a command sequence must always be
expressed as a sequence of unsigned byte values (0-255 decimal; 00 – FF hexadecimal, or
00000000 – 11111111 binary). Each byte in a command sequence being transmitted to the
controller must contain an unsigned binary value. Attempting to code command sequences as
“strings” is not advisable. Any command data being returned from the controller must also
be received and initially treated as a sequence of unsigned byte values. Groups of contiguous
bytes can later be combined to form larger values, as appropriate (e.g., 2 bytes into 16-bit
“word” or “short”, or 4 bytes into a 32-bit “long” or “double word”). For the Lambda DG-4/5
Plus/USB, all Galvo DAC values are stored as “unsigned short” (16-bit) values. A 16-bit value
is transmitted and received to and from the controller as two contiguous bytes.
“Unsigned” means the value can only be positive; negative values are not permitted. A U16
consists of two contiguous bytes, with a byte/bit-ordering format of Little Endian (“Intel”)
(most significant byte (MSB) in the first byte and least significant (LSB) in the last byte). If
the platform on which your application is running is Little Endian, then no byte order
reversal of galvo DAC values is necessary. Examples of platforms using Little Endian
formatting include any system using an Intel processor (including Microsoft Windows and
Apple Mac OS X), and most Linux distributions running on Intel/AMD processor based
systems.