0x0D & 0x0A RS232 communication

[Mitmel]

Hi Everyone,

I´m using the mscomm control included in Visual Basic to perform a serial comunication with the 8051 microcontroller.  The problem is I read back an invalid result (or line feed) everytime the data is 0x0A.  It's suppose to be 0x0A but read back as 0x0D and 0x0A.  How can I fix this?  Is there an example of the code that you can share?

Thanks,

Mitmel

[Jan Axelson]

Post the code that gets the input with the added ODh.

Jan

[Mitmel]

Hi Jan,

Thanks for the reply.  Can I send you the zip file so you can look at it?  If so, can I have your email?

Thanks

[Jan Axelson]

Post the relevant excerpt here.

Jan

[Mitmel]

Hi Jan,

Here's my code:

==================

If rbcomm1(0) = true then
    port = 1
else
    port = 2
end if

me.comm1.commport = port

if me.comm1.portopen = false then
    me.comm1.portopen = true
end if

comm1.settings = "9600,n,8,1"
comm1.inputlen = 1

reg_00 = Asc(serial_device.comm1.input)

==============================

When reg_00 = 0x0A, it reads as 0x0D and 0x0A.  Sometimes it hang up.  I appreciate your help.

Mitch

[Jan Axelson]

What do you mean by "it reads as 0x0D and 0x0A."? Post the code where "it" reads the two values.

Jan

[Mitmel]

Hi Jan,

The code is incldued in the last description.

reg_00 = Asc(serial_device.comm1.input)


The above command is read from the serial port

[Jan Axelson]

Asc Returns an Integer value representing the character code corresponding to a character.

Where are you seeing two character codes?

If this:

Asc(serial_device.comm1.input)

returns 0Dh, the remote device is sending the value.

Jan

[WestfW]

It's pretty common for "lines of text" to be terminated (on a serial line) with both a CR (0x0D) and a LF (0x0A) when the file (unix?) contains only LF (aka "\n")   that's because a vast number of actual serial devices (printers, crt terminals, etc) require both operations (CR == Carriage return == set column to 0, LF == Line Feed == Advance to next line.)

[866JR]

I have been using MScomm for several years with VB6. The MScomm control won't add any characters. I would guess that your 8051 is sending back the 0D & 0A (CR LF) combo. I suggest checking your firmware carefully.