Goal: Configure Simulink to read serial data from a sensor.
BACKGROUND: A serial sensor delivers 3 bytes each second and was validated on a serial terminal. This model is Based on the Mathworks Instrument Toolbox's Simulink Send \ receive example:
OBSERVATION
The "Query Instrument" Block can be configured for COM1,2,3 or 4: not COM13.
I am assuming that the 'Serial Configuration' block is necessary for the model in the sense that it declares \ opens the COM13 port to the Simulink model.
QUESTION
1) Is the 'Query Instrument block' the appropriate block for serial data?
2) Why is the 'Query Instrument block' not configurable to COM13?
In this 'smoke test' example the goal is to display 3 byte serial data #1Hz. Bitwise manipulations will be needed to process status byte and cast the measurement bytes.
The "To Instrument" and "Query Instrument" blocks are older blocks and were hardcoded to only be used for ports COM1-COM4. For a device that's on a different serial port, please try the "Serial Send" and "Serial Receive" blocks to achieve the same functionality. The block parameters dialog for these blocks should auto-populate the list of available COM ports to communicate with so that you can select the proper port for your device.
Related
I would like to read a block of data from my Arduino Mega (and also from an Arduino Micro in another project) with my Raspberry Pi via I2C. The code has to be in Perl because it's sort of a plug-in for my Home-Automation-Server.
I'm using the Device::SMBus interface and the connection works, I'm able to write and read single Bytes. I can even use writeBlockData with register address 0x00. I randomly discovererd that this address works.
But when I want to readBlockData, no register-address seems to work.
Does anyone know the correct register-address, or is that not even the problem that causes errors?
Thanks in advance
First off, which register(s) are you wanting to read? Here's an example using my RPi::I2C software (it should be exceptionally similar with the distribution you're using), along with a sketch that has a bunch of pseudo-registers configured for reading/writing.
First, the Perl code. It reads two bytes (the output of an analogRead() of pin A0 which is set up as register 80), then bit-shifts the two bytes into a 16-bit integer to get the full 0-1023 value of the pin:
use warnings;
use strict;
use RPi::I2C;
my $arduino_addr = 0x04;
my $arduino = RPi::I2C->new($arduino_addr);
my #bytes = $arduino->read_block(2, 80);
my $a0_value = ($bytes[0] << 8) | $bytes[1];
print "$a0_value\n";
Here's a full-blown Arduino sketch you can review that sets up a half dozen or so pseudo-registers, and when each register is specified, the Arduino writes or reads the appropriate data. If no register is specified, it operates on 0x00 register.
The I2C on the Arduino always does an onReceive() call before it does the onRequest() (when using Wire), so I set up a global variable reg to hold the register value, which I populate in the onReceive() interrupt, which is then used in the onRequest() call to send you the data at the pseudo-register you've specified.
The sketch itself doesn't really do anything useful, I just presented it as an example. It's actually part of my automated unit test platform for my RPi::WiringPi distribution.
I'm working on a project where I'd like to be able to send a simple on/off signal back to the PC via one of the modem pins (DSR, DCD, CTS), separate from the standard serial communications.
I'm having trouble accessing these when connecting to the device with the standard VPC serial driver.
Sample Python using pySerial:
import serial
def main(argv):
watchPort(sys.argv[1])
def watchPort(portName):
ser = serial.Serial(portName)
while True:
print("DCD {0}, DSR {1}, CTS {2}".format(ser.cd, ser.dsr, ser.cts))
time.sleep(0.5)
if __name__ == "__main__":
main()
These values are always the same, no matter if the pins are connected HIGH or LOW. I've also tested with a couple terminal programs to verify (CoolTerm, SerialTerm).
I am, however, able to get these values via the D2XX drivers and related APIs, but I'd rather use the simpler serial device method, if possible. Is this not possible?
Why?
I'm setting up a multi-drop RS485 network and planning to use one of these lines as a common signal line that can be used to signal "ready", "error" and to prevent communication collisions.
It turns out that the problem was with the stock FTDI driver that comes with OS X. (see post) Updating to the latest VPC driver fixed it.
I have a Verilog code simulated and synthesized on ISE design toolkit. I've got an FPGA spartan 6 device which is to be used for the implementation. But there is a problem with the device (probably a power issue) which makes the device unavailable in any of the COM ports when I connected it to my PC. So I want to check whether my Matlab code which I made for serial communication through the device does the desired job. So I need a method to test serial communication via any of the COM ports without connecting a serial com device to the PC. Is there any such method that I can Tx Rx serial data from Matlab to COM ports? Any software or any other method would be highly appreciated :)
I found a way to test Matlab serial communication using virtual serial ports.
Download "Freeware Virtual COM Ports Emulator" from: http://freevirtualserialports.com/
I installed it in Windows 10, and it's working (as trial).
Add a pair of two serial ports:
Execute the following Matlab code sample to verify it's working:
s3 = serial('COM3','BaudRate',115200);
s4 = serial('COM4','BaudRate',115200);
fopen(s3);
fopen(s4);
fwrite(s3, uint8([1, 2, 3, 4, 5]));
%fprintf(s3, '12345');
pause(0.1);
RxBuf = fread(s4, 5)
fclose(s3);
delete(s3);
clear s3
fclose(s4);
delete(s4);
clear s4
The output is:
RxBuf =
1
2
3
4
5
Bypassing the problem "it only stays for a single test session".
There is a problem when creating a pair of virtual ports using the software, it only stays for a single test session.
I guess it's a problem with the COM port emulation software.
The following solution, is not a good practice (and not a true solution).
Declare the serial object as global, keeping the object persistent.
Create the serial object only if it's not created.
Don't delete and don't clear the serial object.
See the following code sample:
global s3 s4
if isempty(s3)
s3 = serial('COM3','BaudRate',115200);
end
if isempty(s4)
s4 = serial('COM4','BaudRate',115200);
end
fopen(s3);
fopen(s4);
fwrite(s3, uint8([1, 2, 3, 4, 5]));
pause(0.1);
RxBuf = fread(s4, 5)
fclose(s3);
%delete(s3);
%clear s3
fclose(s4);
%delete(s4);
%clear s4
You can also look for a better virtual COM port software.
As Rotem suggested, if you need to communicate via serial line between 2 program of your PC you need a virtual COM port emulator.
It seems you are running on Windows OS so I would recommend a completely free emulator (not a trial one). For Windows I use com0com Null-modem emulator (from SourceForge).
In the example below I will show how to communicate with "another" device so Matlab will not handle both side of the communication. The other device will be simulated by a simple terminal. For windows I use RealTerm: Serial/TCP Terminal (also from SourceForge).
Setup:
Execute the setup of both program with all default options. by default com0com will create a virtual pair COM3/COM4 but if these port already exist on your system the program may assign other numbers. Check the numbers before you run the example. (it will also create a CNCA0/CNCB0 pair but you can ignore this one for now).
For RealTerm, once installed (don't forget to activate the server registration at the end of the setup, it should be ticked by default though), it will look like below. Keep all default options, just set the port number and the baud rate if they need to be changed.
Test MATLAB -> Terminal
You are ready to send Ascii characters or binary values from MATLAB to your device. The animation below shows you an example of both option:
you can click on the picture to see it full size. It is running in loop so you may want to wait until it restart from the beginning.
Test Terminal -> MATLAB
Below animation shows you how to test the communication in the other way:
Don't forget to tick [CR] [LF] on RealTerm when you send Ascii characters and want to use the '%s' format specifier on MATLAB, as it needs these characters to detect the end of the string.
Note:
If you have another terminal program that you are more used too, it
will work the same.
If the RealTerm option does not suit you, or if you want to handle
both sides of communication from Matlab, then you can use the code
provided by Rotem in his first answer. Just install com0com but
ignore all the RealTerm part.
I have two xbee's series 1. I have them as endpoint devices working in API mode and talking to each other. The first xbee is attached at a raspberry pi, while the other is on my pc where I see the terminal tab of XCTU program. The baud rate I use is 125000.
From raspberry pi I try to send a jpg image which is 30Kbytes. I send data frames 100 byte long (the biggest as it is said in the xbee documentation). Inside a loop I create and send the packets, I have also a cout statement that prints the loop number. Everything is fine and all bytes are sent. When I comment out the cout statement not all bytes are sent.
From what I have understood the cout statement works as a delay between packets, but I still cannot understand why is this happening as it is supposed that I use the half speed ...
I hope I was clear and look forward for a reply.
UPDATE
Just to summarize, i changed baud rate to 250000 where there is the same behavior as in 125000. I also implemented hardware flow control by checking cts signal. When xbees are in transparent mode I need a delay between sending characters at around 150us. The same goes for api mode too. The difference with 125000 baud rate in api mode was that the delay needed, was enough to be betwween each data packet, but in 250000 the delay is needed between each byte that i send. If i do the above everything goes well.
The next thing i did was to plug both xbees in my pc in transparent mode. I went to terminal tab of xctu software where i chose assemble packet and sent at around 3000 bytes to the other xbee. The result was the same. The second xbee received at about 1500 bytes and then each time that i was sending one byte from the first to the second, the "lost bytes" were being received at packets of 1000. :/
So could anyone know what am I doing wrong?
You should connect the /CTS pin from the XBee module into the Raspberry Pi, and have your routine stop sending data when the XBee de-asserts it.
At higher baud rates, it's possible to stream data into the XBee module faster than it can send to the remote module. The local XBee module uses the /CTS pin to notify the host when its buffers are almost full and the host should stop sending. People refer to this as hardware flow control.
It may be necessary to modify the serial driver on the Raspberry Pi to make use of that signal -- it should pause the transmit buffer when de-asserted, and automatically resume sending when re-asserted.
I have a sensor connected to my computer and I downloaded some code that connects it with MATLAB over a serial port.
I have this code which initializes the connection and sets some parameters:
sport = serial(com_port); % assigns the object sport to serial port
set(sport, 'BaudRate', 9600);
... other configs
set(sport, 'Timeout', Timeout);
set(sport, 'ReadAsyncMode', 'continuous');
Where Timeout is a variable set to 5.
What does the set(sport, 'Timeout', Timeout); line actually do? I have looked through MATLAB's Serial Port Devices documentation -Found Here- but I cannot find the documentation on setting a serial port's timeout.
My original idea was that this value was the time my sport object was given to gather data, but the next line, set(sport, 'ReadAsyncMode', 'continuous'); tells the device to continually stream data.
Also, I don't want to go changing too many values without knowing exactly what I'm doing, for fear of breaking anything. Please help!
See the description of the TimeOut property in the matlab documentation.
The property TimeOut sets the "Waiting time to complete a read or write operation"
In the Contents menu on the left you can select other properties, such as ReadAsyncMode and read about them.