writing to serial port (COMM)

[Andreas]

Greetings,

I am just starting to use the COMM package to communicate with a serial
device.
I have found all ports and opened the correct one without problem.
According to the serial device's manual I am supposed to "send AT plus a CR
($41, $54, $0D) and await the same answer". The problem is that I am not
sure how to transfer "AT plus a CR".
I have seen in a few examples (in this group's archives) how you can write
to a serial port, and I am doing the following:

CommPortIdentifier portId =
CommPortIdentifier.getPortIdentifier("COM2");
SerialPort serialPort = (SerialPort)portId.open( "MySerialApp", 2000 );
serialPort.getOutputStream().write("AT <CR>".getBytes());

I am guessing this is not how it should be done (the "AT <CR>" I mean).
After you all have recovered from your laughing attacks, maybe someone
could help me understand this basic stuff?
It would be greatly appreciated.

Best,
Andreas

 

[Knute Johnson]

Greetings,

I am just starting to use the COMM package to communicate with a serial
device.
I have found all ports and opened the correct one without problem.
According to the serial device's manual I am supposed to "send AT plus a CR
($41, $54, $0D) and await the same answer". The problem is that I am not
sure how to transfer "AT plus a CR".
I have seen in a few examples (in this group's archives) how you can write
to a serial port, and I am doing the following:

CommPortIdentifier portId =
CommPortIdentifier.getPortIdentifier("COM2");
SerialPort serialPort = (SerialPort)portId.open( "MySerialApp", 2000 );
serialPort.getOutputStream().write("AT <CR>".getBytes());

I am guessing this is not how it should be done (the "AT <CR>" I mean).
After you all have recovered from your laughing attacks, maybe someone
could help me understand this basic stuff?
It would be greatly appreciated.

Best,
Andreas

"AT\r".getBytes() or byte[] buf = { 0x41, 0x54, 0x13 };

CR is a nmenonic for carriage return.

 

[Andreas]

"AT\r".getBytes() or byte[] buf = { 0x41, 0x54, 0x13 };

CR is a nmenonic for carriage return.

Thank you Knute.
It actually struck me when I looked up the ASCII-codes for the hex-numbers.
(duh..)

Best,
Andreas

 

[Roedy Green]

It actually struck me when I looked up the ASCII-codes for the hex-numbers.

if the problem is remembering the hex, decimal or octal codes, see
http://mindprod.com/jgloss/ascii.html

 

[Andreas]

if the problem is remembering the hex, decimal or octal codes, see
http://mindprod.com/jgloss/ascii.html

Thanks. I'm sure that table can come in handy.

 

[Thomas Weidenfeller]

Thank you Knute.
It actually struck me when I looked up the ASCII-codes for the hex-numbers.
(duh..)

But some of the hex codes for ASCII are easy to remember:

A few easy to remember characters are:

0x00: NUL
0x20: space
0x30: '0'
0x40: '@'
0x7f: DEL

Knowing these then help for other characters:

Digits 0-9:

0x30 is '0', 0x39 is '9'. digit + 0x30 = ASCII code of digit.

Uppercase letters:

0x40 is '@', after that the uppercase letters start, and are easy to
count. 0x41 = 'A', 0x42 = 'B' ... Position of letter in alphabet + 0x40
= uppercase letter's ASCII code.

Lowercase letters:

+ 0x20 offset from uppercase letters. Easy to count.


Some things are even easier to remember in octal. 0100 is '@'.

/Thomas

 

[blackmonk]

Hi guys, i know this is old and all but i'm trying to read input from a weight scale and output it to a gui i've created. I'm very new to java and i'm using this package (javax.comm)for the first time. pls help with any code that you might have that reads from a serial port. My scale connects to the pc using a usb-serial converter.