Connecting GPIB to an External Device Using MATLAB
Is there a way to establish a GPIB connection using MATLAB without the tool control toolbox? (I don't have it). There is also a way that MATLAB can know what the parameter values of an external RS232 device are (baud rate, stop bit, etc.). For RS232 connection, I have the following code:
% This function is meant to send commands to Potentiostat Model 263A.
% A run includes turning the cell on, reading current for time t1, turning
% the cell off, waiting for time t2.
% t1 is the duration [secs] for which the Potentiostat must run (cell is on)
% t2 is the duration [secs] to on after off
% n is the number of runs
% port is the serial port name such as COM1
function [s] = Potentiostat_control(t1,t2,n)
port = input('type port name such as COM1', 's')
s = serial(port);
set(s,'BaudRate', 9600, 'DataBits', 8, 'Parity', 'even', 'StopBits', 2 ,'Terminator', 'CR/LF');
fopen(s)
%fprintf(s,'RS232?')
disp(['Total runs requested = ' num2str(n)])
disp('i denotes number of runs executed so far..');
for i=1:n
i
%data1 = query(s, '*IDN?')
fprintf(s,'%s','CELL 1'); % sends the command 'CELL 1'
%fprintf(s,'%s','READI');
pause(t1);
fprintf(s,'%s','CELL 0');
%fprintf(s,'%s','CLEAR');
pause(t2);
end
fclose(s)
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For your GPIB question, is there a callable library on the GPIB card (DLL if you are on Windows)? Matlab has an interface for calling external libraries . The main procedure is for Matlab to parse the header file with LOADLIBRARY
, then view the available functions with LIBFUNCTIONS
and call the functions using CALLLIB
.
For your RS232 question, I don't think there is any way for the node side to know the device side parameters without external documentation.
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I am using National Instruments VISA and NI 488.2 .
First make sure you check VisaNS.NET API
in the NI-VISA setup, see the following figure:
I am using NationalInstruments.VisaNS.MessageBasedSession
through the .NET interface from MATLAB.
I wrote the following MATLAB class that brings NI VISA to MATLAB:
classdef Visa
properties
vi
SrqMask
SrqTimeout
end
methods
function obj = Visa(resourceName)
NET.addAssembly('NationalInstruments.VisaNS');
obj.vi = NationalInstruments.VisaNS.MessageBasedSession(resourceName);
obj.SrqMask = '*CLS;*ESE 1;*SRE 32';
obj.SrqTimeout = 10000;
end
function obj = delete(obj)
obj.vi.Dispose();
end
function obj = Dispose(obj)
obj.vi.Dispose();
end
function obj = Write(obj, data)
obj.vi.Write(data);
end
function data = ReadString(obj)
data = char(obj.vi.ReadString());
end
function data = ReadByteArray(obj)
data = obj.vi.ReadByteArray();
end
function data2 = Query(obj, data)
data2 = char(obj.vi.Query(data));
end
function obj = SrqBegin(obj)
obj.vi.EnableEvent(NationalInstruments.VisaNS.MessageBasedSessionEventType.ServiceRequest, ...
NationalInstruments.VisaNS.EventMechanism.Queue);
obj.vi.DiscardEvent(NationalInstruments.VisaNS.MessageBasedSessionEventType.ServiceRequest);
obj.Write(obj.SrqMask);
end
function status = SrqEnd(obj)
evt = obj.vi.WaitOnEvent(NationalInstruments.VisaNS.MessageBasedSessionEventType.ServiceRequest, ...
obj.SrqTimeout);
evt.Dispose();
status = obj.vi.ReadStatusByte();
obj.vi.DisableEvent(NationalInstruments.VisaNS.MessageBasedSessionEventType.ServiceRequest, ...
NationalInstruments.VisaNS.EventMechanism.Queue);
end
function obj = SrqWrite(obj, data)
obj.SrqBegin();
obj.Write(data);
obj.SrqEnd();
end
function data2 = SrqQuery(obj, data)
obj.SrqBegin();
obj.Write(data);
obj.SrqEnd();
data2 = obj.ReadString();
end
end
end
I have also added some methods to handle SRQ request.
In the following code, you can control the GPIB tool, for example:
resourceName = 'GPIB0::20::INSTR'; % GPIB adapter 0, Instrument address 20
vi = Visa(resourceName);
idn = vi.QueryString('*IDN?');
A MessageBasedSession
can be used to communicate with your instrument via GPIB, Ethernet, or USB.
See. Also fooobar.com/questions/1118171 / ... .
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I don't know about the RS232 parameters, but for a tcpip instrument, you can send SCPI commands very easily.
Here is an example where I am sending SCPI command to Rohde & Schwarz instances. No visa or IVI required. Use port 5025.
t = tcpip('147.214.90.136', 5025);
fopen(t);
fprintf(t, '*IDN?');
fprintf(1, DataReceived)
Then close the connection when you're done:
fclose(t);
delete(t);
clear t
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