Transcript 儀器電控(一) - 網頁變動公告

儀器電控
陳彥穆
July 11, 2008
Outline
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Computer-based Measurement Automation
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Labview
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Introduction
Control Examples –
Matlab
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Design Flow
A Comprehensive Overview & some history
Introduction
Control Examples – Graphic User Interface Design
Comparison
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Merits and Defects
Hybrid
Instrument Control !?
The abilities to
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Write
Write some bits or bytes to the instruments as commands
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Read
Read information or measured data from the instruments
Instrument Control !?
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In order to do that, we require
Interface
Physical connections between computers and instruments
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Interface driver
It tells computers how to interpret the data on the interface
( Protocols )
Instrument Control !?
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and we still need
Command book
The language of “the” instrument.
We call a complete and well-capsulated command set as
“Instrument Driver.”
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Control Program
combinations of commands to finish our job
Why?
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Save time and man power
Your instrument has no front panel
(CAMAC VXI PXI)
Part-I: Design Flow
Measurement Automation
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Design flow
Problem Define
The Control Flow Chart
Nature of Signal
Instruments
Programming
Programming Language /
Environment
Instrument Command
Interface Drivers
User Interface
Testing
•Control Procedure
• Type?
Magnitude?
Duration?
• Resolution?
Dynamic Range?
Field of View?
• Instrument Interface
• VB, C/C++, VC.Net, BCB…
• Matlab
• Labview
• Serial port driver
• GPIB driver
• USB driver
• Instrument Command
Problem Define: The control flow chart
A sample control flow chart
Problem Define: Nature of signal
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Type
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Electrovoltage/current
impedance
Photon
wavelength
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Magnitude
Duration
Problem Define: Instruments
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Resolution
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Dynamic Range
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Intensity
Time response of instrument
Intensity
Frequency
Field of View
Instrument Interface
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Crate Instrument: CAMAC / VXI / PXI
GPIB / RS-232 / USB / IEEE1394
PCI / ISA
A real example:
measure laser contrast automatically
A real examplemeasure laser contrast automatically
Control Flow Chart
A real examplemeasure laser contrast automatically
The Instruments
A real examplemeasure laser contrast automatically
The Instruments
Increase dynamic range by filters, which can be changed by
a stepping motor.
Programming :
Programming Language / environment
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text-based languages
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C/C++, VC.Net, BCB
Visual Basic
Matlab (Scientific environment)
graphical programming language
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Labview
Programming :
Instrument Command / Interface Drivers
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Interface Drivers
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Serial port driver
GPIB driver
USB driver …
VISA (Virtual Instrument Software Architecture)
Instrument Command
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SCPI (Standard Commands for Programmable Instrumentation)
VXI Plug&Play
IVI (Interchangeable Virtual Instrument )
Instrument specific command
Part-II: History
A Comprehensive Overview of Measurement
Automation
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CAMAC (Computer Automated Measurement And Control)
A CAMAC “crate”
CAMAC is an IEEE-standard (583),
modular, high-performance, real-time
data acquisition and control system
concept born in 1969.
擷取自 http://www.kscorp.com
Register-based command
A Comprehensive Overview of Measurement
Automation
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GPIB (General Purpose Interface Bus / IEEE-488)
For monolithic instruments
Text-based command
1965
1975
1987
1990
1993
A Comprehensive Overview of Measurement
Automation
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VXI (VME eXtensions for Instrumentation / IEEE-1155) 1987
Text-based / Registerbased command
擷取自
Matlab Instrument Control Toolbox Help documents
A Comprehensive Overview of Measurement
Automation
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Serial Port
RS-232 COM1
very common on personal computers
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Parallel Port
printer port LPT
Difficulties in developing a measurement
automation system
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Differences in all Instruments
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every company has its own interface
every instrument has its own command
Different software support in different environments
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Interface driver for UNIX / DOS / Window/ …
Instrument driver written in C/ Fortran/
Non-Interchangeable
Time inefficient
A Comprehensive Overview of Measurement
Automation
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VISA (Virtual Instrument Software Architecture)
Is a superset of all interface driver
(from VXI plug&play)
Computer Industry Standards
(DDE, DLL, OLE, TCP/IP, etc.)
Vendor A
Vendor B
End Users
Vendor C
Application
Software
Environment
Test
Executive
Application
Application
Programs
Instrument
Programming
Tool
VISA API
NI-488.2
API
NI-VXI
API
Other
API
Other
API
A Comprehensive Overview of Measurement
Automation
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VISA provides us a unified communication “channel” from
your program to the instrument with any physical interface.
VISA-GPIB, VISA-VXI, VISA-serial port, VISA-TCP/IP …
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Same I/O function for open, send, read, query, close…, but
not same command.
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Now, The VISA specifications, formerly maintained by the VXI
plug&play are now being maintained by the IVI.
A Comprehensive Overview of Measurement
Automation
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IVI (Interchangeable Virtual Instrument)
The IVI standards define an open driver architecture, a set of
instrument classes, and shared software component.
A Comprehensive Overview of Measurement
Automation
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Utilizing VISA to achieve interface I/O (other interface drivers are also available)
IVI defines several Instruments class to achieve same “command”
( just like SCPI)
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DC power supply
Digital multimeter (DMM)
Function generator & Arb
Oscilloscope
Power meter
RF signal generator
Spectrum analyzer
Switch
The IVI Config server – for instrument interchangeability
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Two instruments with different vendors, different interfaces (e.g. GPIB
and USB) can be interchanged just in a few minutes.
The Structure
Software
Application
IVI class driver
Instrument
driver
VISA
others
Most of the time, we start
here……
GPIB/VXI/USB/serial… interface drivers
Or just VISA
Hardware
Interface
Instrument Hardware
GPIB/CAMAC/VXI/USB interface
Part-III: LabVIEW
What is LabVIEW?
LabVIEW (Laboratory Virtual Instrument
Engineering Workbench) is a program
development application, much like C or
BASIC.
However, other programming systems use
text-based languages to create lines of code,
while
LabVIEW
uses
a
graphical
programming language, G, to create programs
in block diagram form.
Writing programs in Labview is just like building
real instruments.
Front Panel
The GUI of your program
VI : Virtual Instrument
The front panel is the graphical user
interface of your LabVIEW VI. This
interface collects user input and
displays program output. The front
panel can contain knobs, push
buttons, graphs, and other controls
and indicators.
Block Diagram
The source code of your program
The block diagram contains the
graphical source code of your VI
(Virtual Instrument). In the block
diagram, you program your VI to
control and perform functions on
the inputs and outputs you
created on the front panel.
The block diagram can include functions and structures from the built-in
LabVIEW VI libraries. It also can include terminals that are associated with
controls and indicators created on the front panel.
Front panel demo: a virtual instrument
…\examples\apps\demos.llb\Two Channel Oscilloscope.vi
Controls and indicators
Palettes
LabVIEW palettes give Functions Palette
you the options you need
to create and edit your
front panel and block
diagram.
Controls Palette
Front panel / Block diagram
Tools Palette
Data Flow
LabVIEW VIs follow a dataflow
model for program execution. The
block diagram consists of nodes
such as VIs, structures, and
terminals from the front panel.
These nodes are connected by
wires, which define the flow of data
through the program. The execution
of a node occurs when all its inputs
are available. When a node finishes
executing, it releases all its outputs
to the next node in the dataflow
path.
Arithmetic
z = sqrt(abs(x)) + y;
One may use a
formula node:
Boolean algebra
D = A AND (B OR C)
diagram
panel
Comparison and CASE structure
if a > b then
todo list 1……
else
todo list 2……
end
FOR loop
C++ code:
a=1;
for (i=0, i<6, i++){
a=a+a*i;
}
Output = 720
LabVIEW diagram:
Sequence and While loop
sequence
while loop
Graph and chart
Example: plot a sine wave
Mechanical Action
Switch When Released
Switch When Pressed
Latch When Pressed
Switch Until Released
Latch Until Released
Latch When Released
RS-232 pin assignments
6
7
8
9
1
2
3
4
5
PC serial
port
9 way Dconnector
1
Signal
Full name
RLSD
Received Line Signal Detect
2
RxD
Receive Data
3
TxD
Transmit Data
4
DTR
Data Terminal Ready
5
GND
Ground
6
DSR
Data Set Ready
7
RTS
Request To Send
8
CTS
Clear To Send
9
RI
Ring Indicator
Output from computer
Input to computer
Remote control using RS-232
Some parameters to know before using the serial port
1. Port number:
port number = 0 for COM1, 1 for COM2
2. Baud rate (or bits per sec, bps)
3. Data bits: number of bits in the incoming data
4. Number of stop bits
5. Parity bit? (None, Odd, Even)
6. Command characters used by the device
Find parameters 2~6 from the manual of the device!
RS-232 Serial character frame
Marking level
Spacing level
Time
8 data bits
Start bit
(always spacing state)
Parity bit
Stop bits
(always marking state)
Serial Port VIs in (Labview 6.1 or older version)
(Functions»Instrument I/O»Serial)
Serial Port Init
Initializes the selected serial port to
the specified settings.
Bytes at Serial Port
Returns in byte count the number of
bytes in the input buffer of the serial
port indicated in port number.
Serial Port VIs (Cont.)
Serial Port Read
Reads the number of characters
specified by requested byte count
from the serial port indicated in
port number.
Serial Port Write
LabVIEW Function and VI
Reference Manual 36-2 Writes
the data in string to write to the
serial port indicated in port number.
VISA Serial Port VIs in (Labview 7.0 or later version)
(Functions»Instrument I/O»Serial)
VISA Serial Port Init
Initializes the selected serial port to
the specified settings.
VISA Open
Open the VISA channel according
the VISA resource name
VISA Close
Close the VISA channel according
the VISA resource name
Serial Port VIs (Cont.)
VISA Read
Reads the number of characters
specified by requested byte count
from the VISA interface indicated
in VISA Resource name.
VISA Write
LabVIEW Function and VI
Reference Manual 36-2 Writes
the data in string to write to the
VISA interface indicated in VISA
Resource name.
VISA Resource
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The MAX (Measurement Automation eXplorer)
A GUI tool to manage and test your instruments
VISA driver
It usually comes along with
Labview or you can simply
download it from www.ni.com
Your Interface information
Some handy knowledge
about this Interface
Part-IV: MATLAB
What is Matlab?
MATLAB is a high-performance language
for technical computing. It integrates
computation, visualization, and
programming in an easy-to-use
environment where problems and solutions
are expressed in familiar mathematical
notation.
MATLAB 7 R14
>> tmtool
Instrument Control Toolbox Test&Measuement Tool
just like the MAX of Nation Instrument
How to use GPIB in Matlab
>>help gpib
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GPIB Construct GPIB object.
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OBJ = GPIB('VENDOR',BOARDINDEX,PRIMARYADDRESS) constructs a
GPIB object, OBJ, associated with board index, BOARDINDEX, and
instrument primary address, PRIMARYADDRESS. The primary address
can range between 0 and 30. The GPIB hardware is supplied by
VENDOR. Supported vendors include:
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'agilent' - Agilent Technologies hardware.
'cec'
- Capital Equipment Corporation hardware.
'contec' - CONTEC hardware.
'ics'
- ICS Electronics hardware.
'iotech' - IOTech hardware.
'keithley' - Keithley hardware.
'mcc'
- Measurement Computing Corporation (ComputerBoards) hardware.
'ni'
- National Instruments hardware.
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GPIB (IEEE-488) bus history
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GPIB (General Purpose Interface Bus / IEEE-488)
For monolithic instruments
Text-based command
1965
1975
1987
1990
1993
Pin assignment of GPIB
Signal Line: 16
Ground and Shield: 8
Data Line: 8
Management Line: 5
Handshake Line: 3
擷取從 MATLAB HELP
GPIB (IEEE-488) bus topology
Listeners can only receive data and commands from the bus.
Talkers can transmit data to other devices.
The controller supervises the transfer of data along the bus.
This role is usually performed by a PC.
Data-acquisition interface devices
Parallel buses possess a separate signal line for each bit,
enables a byte to be transmitted in one operation.
Serial buses transfer one bit at a time along a single
conductor.
GPIB
RS-232
RS-485
type
parallel
serial
serial
Bandwidth
1-8 Mbytes/s
<20 Kbytes/s
<20 Kbytes/s
Max. number of devices
14
1
32
Max. cable length
20 m
15 m
1220 m
IEEE-488 bus lines
8 bi-directional data lines, DIO1 – DIO8.
Data transfer handshake lines,
DAV:
Data Valid
Asserted by talker to indicate bus holds valid data.
NRFD: Not Ready For Data
Asserted by listener to indicate that it cannot receive data.
NDAC: Not Data Accepted
Asserted by listener while reading data.
IEEE-488 handshaking sequence
Talker
Attention
Talker
Data Valid
Talker
Listener
Not Ready For Data
Listener
Not Data Accepted
All signal lines use active low, TTL logic levels.
IEEE-488 bus lines
Interface management lines,
IFC:
Interface Clear
Asserted by controller to initialize all bus devices.
ATN:
Attention
Asserted by controller to indicate that the data bus holds a
command rather than data.
REN:
Remote enable
Asserted by controller to disable any front panel controls.
EOI:
SRQ:
End or Identity
Asserted by talker to identify the last byte of data in a block.
Service Request
Asserted by any device to request the attention of the controller.
GPIB
%Suppose We have a NI GPIB card with board index 0 Primary address 1
>>g = gpib(‘ni’, 0, 1);
%To connect the GPIB object to the instrument:
>>fopen(g)
% To query the instrument.
>>fprintf(g, '*IDN?');
%Identify yourself or else…
>>idn = fscanf(g);
% To disconnect the GPIB object from the instrument.
>>fclose(g);
It’s just like writing/reading to/from a file
>>instrhelp gpib %for further help, or
>>doc gpib
%open the help
How about serial port
First, check it out in the command line
>>help serial
And you’ll find it almost the same with GPIB
%Suppose we have a serial port ‘com1’, and we want to set its BaudRate to
%1200
>>s1 = serial('COM1', 'BaudRate', 1200)
>>fopen(s1)
% To query the instrument.
>>fprintf(s1, '*IDN?');
%Identify yourself or else…
>>idn = fscanf(s1);
% To disconnect the serial port object from the instrument.
>>fclose(s1);
Matlab vs. Labview
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serial('COM1', 'BaudRate', 1200)
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fopen(s1)
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fprintf(g, '*IDN?');
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fscanf(s1);
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fclose(s1);
How to use VISA interface
•MATLAB has it own GPIB and serial port driver, but
you can still use the version in VISA library (vmtool)
% To construct a VISA-GPIB object connected to Board 4 with an
% instrument with primary address 1 and no secondary address.
>>g = visa('ni', 'GPIB4::1::0::INSTR');
% To construct a VISA-VXI object that communicates with a VXI
% instrument located at logical address 8 in the first VXI system.
>>v = visa('agilent', 'VXI0::8::INSTR');
% To construct a VISA-serial object that is connected to COM1 with
%BaudRate 1200.
>>s=visa(‘ni’,’ASRL1::INSTR’,’BaudRate’,1200)
%still
>>fprintf(g,’*IDN?’)
>>fscanf(s)
>>inspect(s) %GUI tool for checking all the properties of this object
Basic building blocks of GUI
and Event-driven programming in Matlab
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Figure – a front panel of your program
Uicontrol
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Check boxes
Editable text fields
List boxes
Pop-up menus
Push buttons
Radio buttons
Sliders Static
text labels
Toggle
buttons
圖擷取從 MATLAB程式設計與應用-張智星
Basic building blocks of GUI
and Event-driven programming in Matlab
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Callback functions
figure
h = uicontrol(gcf,'Style','Push','position',[50 20 80 30],'string',‘Push');
cmd = 'fprintf(''Somebody pushed me!\n'');';
set(h, 'Callback', cmd);
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Figure and Object Handle
擷取從 MATLAB程式設計與應用-張智星
Some useful commands
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findobj
Locate graphics objects with specific properties
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gcf
Get current figure handle
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gca
Get current axes handle
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gcbo
Return handle of object whose callback is executing
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set / get
set / get properties of object
Measurement Automation in Matlab
High Voltage Main Frame
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Retard.m
Serial Port
LPT
Pin2 and pin7
FireBox
Pressure
Watcher
Laser Intensity
monitor
PC
MATLAB
GPIB
Oscilloscope
Laser System
MCP
grid
Part-V: Comparison
Labview > Matlab
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Labview
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G-Language (Graphic)
great GUI
fast response
Multi-threading-embedded
Matlab
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M file (Text)
Limited GUI
Interpreter (Slow)
Single threading (M file)
readasync
擷取從 Labview Documentation
Matlab > Labview
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Matlab
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M file (Text), handle string well
Unlimited algorithms and it’s easy to add your own
It’s easy to modified your subroutine
Comment and Documentation
Labview
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lots of algorithms but it takes a while to locate it.
“draw” another one?
Connector adding
Show dataprocess.vi
It is messy to write documentation
Matlab == Labview
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Matlab
Instrument Control ability
Serial port, GPIB interface, VISA driver
Instrument Driver, tmtool
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Instrument driver editor – write your own or load it from IVI driver
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Labview
Instrument Control ability
Serial port, GPIB interface, VISA driver
Instrument Driver, IVI, MAX
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Outsourcing
They are both capable of calling other program or being called
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Matlab (External Interfaces)
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Call other DLL ( MATLAB Interface to Generic DLLs )
To be a COM server or client
Calling C from Matlab ( MEX-File wrapper )
Labview
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DLL Invoke node
ActiveX Invoke node
Matlab Script node
CIN Code Interface Node – to call C code
How to enhance the GUI in MATLAB
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Adding ActiveX Controls
>>h = actxcontrolselect;
>>h.get;
>>h.invoke;
>>methods(h);
>>methodsview(h);
How to design a program?
How to design a program?