Bc2000 (for the BCF2000 & BCR2000)

Hi
> # Hall Mode 0-7
> 
> $encoder 1
>    .showvalue on
>    .mode 1dot
>    .resolution 24 24 24 24
>    .default 0
>    .minmax 0 7
>    .tx $F0 $41 $10 $00 $18 $12 $40 $01 $30 val $0F $F7
> 
> But it doesn't work. i know that the checksum "0F" need to be calculated
> from 40 01 30 00

Nearly right
.tx $F0 $41 $10 $00 $18 $12 $40 $01 $30 val cks-1 cks_start $F7
In your case...
.tx $F0 $41 $10 $00 $18 $12 $40 $01 $30 val cks-1 $06 $F7

$F0 sysex start
$41 Roland
$10 device id
$00 $18 model id
$12 command - here is the parameter data
$40 $01 $30 parameter address (should there be 4 bytes here??)
val parameter value
cks-1 the checksum result. cks-1 is the calculation that Roland uses
$06 the start of checksum calc. 

Roland only uses the address and the value data, not the header, when working out the checksum.
That is, the checksum calculation starts by adding the bytes from the address bytes (byte 6 - $F0 is byte 0) to the end of the value bytes.

All the best
Royce