Writing Hex to Serial

General
1

Hi all!

I’m communicating with a serial device which wants values in hex bytes. hence If I want to send e.g. 45 in hex, I have to

1: create a string: “&h45”
2: get decimal value of that string: theDecimalValue = val("&h45")
3: serial1.Write chrb(theDecimalValue)

is there a more elegant way? It’s probably as simple as 1,2,3 but hex, decimal and binary is annoying :slight_smile:

thanks!

2

what code leads up to the point where you know you need to write hex 45 ?
There may be a more elegant way but knowing how you determine that you need to send &h45 might be relevant

3

DecodeHex function may help.

4

or maybe better use memory blocks:

dim m as new memoryblock(4) m.Int8Value(0) = &h45 m.Int8Value(1) = 12 m.Int8Value(2) = 34 m.Int8Value(3) = 56 serial1.Write m

to send a package with 4 bytes in this case.

5

[quote=244702:@Norman Palardy]what code leads up to the point where you know you need to write hex 45 ?
There may be a more elegant way but knowing how you determine that you need to send &h45 might be relevant[/quote]

There’s a table of commands to send, so e.g. &h45 does one thing and &h49 does another, and some take a decimal value that has to be split in two hex bytes, so e.g. 350 (15E) must be sent as &h01 &h5E …

6

would seem a lookup table configured at app start up would work

7

then still variable values need to go through decimalVal = val(&hXX) and then serial.write chrb(decimalVal) … not that bad anyway.

thanks!

8

You don’t need to convert to decimal. ChrB(&hXX) will work just fine.

9

Only up to values of 255 (&hFF). Beyond that, you have to do some math.

dim s as string

if n >= 256 then
  dim m as integer = n \\ 256
  n = n mod 256
  serial1.Write ChrB( m )
end if

serial1.Write ChrB( n )

Or something like that. I’m still a little unclear about what the receiver is wanting.

10

Thanks to all, memoryblock worked just fine…

cheers and Xojo is awesome!

11

[quote=244730:@Shant Khatcherian]then still variable values need to go through decimalVal = val(&hXX) and then serial.write chrb(decimalVal) … not that bad anyway.

thanks![/quote]

I’d actually create a class that has each command listed that can give you back the right bytes for the command + parameters

Stuff the parameters into a memoryblock and then write the memoryblock using bytes

12

Hi
I use structures for data send.
Structure DATA
start as uint8
value as byte
End Structure

Dim a as DATA
a.start=chr (&h45)
a.value=a.start.val
serial.write a.stringvalue (true)

I’m not sure if its literally like this. (I’m writing it from memory)

regards
Kris

13