WRF command VNC1L, VDIP1

[John Chris]

Hi there,

I'm using the 28X1 to communicate with the Vinculum VDIP1 using the hardware serial pins. A command such as this,

'HSEROUT 0,("WRF ",$00,$00,$00,$08,CR,"AAAAAAA",CR)

that I found in an archived post does what one would want - that is, write chars to an open file. In this case it writes seven 'A' characters and a new line. This works.

I don't understand, however, why the three $00 are necessary? I accept it, just don't understand it.

Might someone dissect the above command and explain what is happening?

For reference, the firmware users manual is called: 'UM_VinculumFirmware_V205.pdf' and is easily found (a little too large to post)

Thanks

 

[Technical]

You are sending 8 bytes of data (7 As and final CR)

The WRF command requires a dword (double word, 4 bytes) telling how much data is to be sent followed by a cr, followed by that actual data.

As you are sending 8 bytes, that is then $00, $00, $00, $08, CR

If you were sending 259 bytes (which is (1x256) + (3x1) ) it would be $00, $00, $01, $03, CR