Active10 months ago

This class can be used to communicate with a serial port under Linux or Windows. It takes the path (like '/dev/ttyS0' for linux or 'COM1' for windows) of serial device and checks whether it is valid before opening a connection to it. Once the connection is opened, it can send data to the serial port. On Linux, all serial ports are driven the same way. Only their device nodes are changing to reflect the port type: i.MX processor internal ports. Php serial communication in linux. I have installed xampp in fedora 13.I am trying to communicate with microcontroller through serial port using php serial class. In this post I will cover five conman utilities used for serial communication under Linux / Unix / *BSD and Mac OS X. Find out information about your serial ports Type the following dmesg command. This is a step-by-step guide to using the serial port from a program running under Linux; it was written for the Raspberry Pi serial port with the Raspbian Wheezy distribution. However, the same code should work on other systems.

I'm having a problem reading from a serial device on Linux. The problem is rather weird, and I wasn't able to nail down the causes.

I'm opening the /dev/ttyUSB0 file with PHP and beginning to communicate with the device according to the device's protocol. Many times I encountered a situation where the PHP script waits for the device to respond. When I ran a Perl script in parallel which supposed to do the same it sent a request to the same device, and quit supposedly without getting a response. Then I saw that the PHP script got the response (only after the Perl script sent a request).

I encountered a similar matter when trying to read Arduino with PHP. The PHP got no response from the port, but Arduino IDE's Serial Monitor printed it.

I think I'm missing a crucial thing about Linux files and USB ports here. What might be the problem? How can I tell which programs use the port/file?

MeLightMeLight

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1 Answer

Check these two articles on my wiki. The first article describes how to set useful permissions on the device node. The second article is an example that prints out all data that the remote sends to the PC. Although written for Arduino it is easily ported for other uses.

Using lsof you can find out which program is currently using the port:

lsof | grep /dev/ttyUSB0cat_ttyUS 19182 jhendrix 3u CHR 188,0 0t0 14519955 /dev/ttyUSB0

With the stty commands you don't lock the port for exclusive use.

jippiejippie

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Active4 years ago

I have a piece of simple code that works on a Windows - WAMP environment, e.g.

It connects via a USB cable (using USB-Serial drivers) to a circuit-board to light some LEDs, and it works fine - so similarly windows software like 232Analyser, can connect to COM3 and send code in DEC like 1,255,255,255,255,5, and light the LEDs. The number 255, is a DEC number from: 1,2,4,8,16,32,64,128,255 which will light a certain LED depending on which number is called.

Anyway, the code above works fine on Windows, and lights LEDs by calling this PHP file. So can call a URL like: http://localhost/lightled.php which works ok.

Now I need it to work via Linux, on a Raspberry Pi, so I have just installed standard Raspberry Linux, and Apache with PHP.

Then attached the USB cable, and it appears as /dev/ttyUSB0 I have then CHMOD 777 /dev/ttyUSB0

And changed the PHP code to:

However calling this file on Linux in a browser is not Lighting the LEDs, as it does on Windows.

Now when I call this file it goes through with no errors, without chmod 777, it gave a permission denied error. So it seems like it goes through ok, but something else is wrong.

So question is anyone know how to make it work on Linux, it might be I am calling the USB wrong, or Raspberry Linux needs some kind of drivers, or ' `mode ' needs to be defined differently ...or maybe the decimal/binary code sent is not right like 'chr(2)' etc. needs to be different and wont be sent in same way on a LAMP setup.

Any ideas on what I can try?

Thanks.

aku fooaku foo

1 Answer

There is no mode command in Linux.

The closest equivalent is stty, but it doesn't take identical command-line arguments. You will need to perform some translation; read the manual page for stty for details.

Linux Serial Port Software

duskwuffduskwuff

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Linux Serial Port Software

Linux Serial Port Programming

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Php Serial Port Communication Linux Distro