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rINSTCONTROL/@MyNewpUsbComm/MyNewpUsbComm.m
7b5f655686a3TekRSA-Freq-vs-Time

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MyNewpUsbComm.m
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classdef MyNewpUsbComm < MySingleton
properties (GetAccess = public, SetAccess = private)
% Driver in use
isbusy = false
end
properties (Access = public)
% An instance of Newport.USBComm.USB class
Usb
end
methods(Access = private)
% The constructor of a singleton class should only be invoked from
% the instance method.
function this = MyNewpUsbComm()
disp(['Creating a new instance of ' class(this)])
loadLib(this);
end
end
methods(Access = public)
% Load dll
function loadLib(this)
dll_path = which('UsbDllWrap.dll');
if isempty(dll_path)
error(['UsbDllWrap.dll is not found. This library ',...
'is a part of Newport USB driver and needs ',...
'to be present on Matlab path.'])
end
NetAsm = NET.addAssembly(dll_path);
% Create an instance of Newport.USBComm.USB class
Type = GetType(NetAsm.AssemblyHandle,'Newport.USBComm.USB');
this.Usb = System.Activator.CreateInstance(Type);
end
function str = query(this, addr, cmd)
% Check if the driver is already being used by another process.
% A race condition with various strange consequences is
% potentially possible if it is.
assert(~this.isbusy, 'Newport Usb Comm is already in use.')
this.isbusy = true;
% Send query using QueryData buffer. A new buffer needs to be
% created every time to ensure the absence of interference
% between different queries.
QueryData = System.Text.StringBuilder(64);
stat = Query(this.Usb, addr, cmd, QueryData);
if stat ~= 0
warning(['Query to Newport usb driver was unsuccessful.'...
errorCodeToMessage(this, stat)]);
end
str = char(ToString(QueryData));
this.isbusy = false;
end
end
methods (Access = private)
% Convert the code returned by read/write/query functions to
% a message
function str = errorCodeToMessage(~, stat)
switch stat
case 0
% No error
str = '';
case -2
str = 'Error: Device timeout';
case 1
str = 'Error: Duplicate USB address';
otherwise
str = sprintf('Error Code = %i', stat);
end
end
end
methods(Static)
% Concrete implementation of the singleton constructor.
function this = instance()
persistent UniqueInstance
if isempty(UniqueInstance) || ~isvalid(UniqueInstance)
this = MyNewpUsbComm();
UniqueInstance = this;
else
this = UniqueInstance;
end
end
end
end
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