113. Altering the RS423 format
~~~~~~~~~~~~~~~~~~~~~~~~~
If you are experimenting with the RS423 serial port, and need to alter the
data format, then you can do so with the command *FX156,X,227 . The value of
X can be looked up in the table below, where X is 4*n. The default value on
the Beeb is n=5, corresponding to *FX156,20,227 .
DATA BITS PARITY STOP BITS n X
--------- ------ --------- - --
7 even 2 0 0
7 odd 2 1 4
7 even 1 2 8
7 odd 1 3 12
8 none 2 4 16
8 none 1 5 20
8 even 1 6 24
8 odd 1 7 28
You can read the current value of n using the following function. If you want
to read the value of X rather than of n, then change the &400 in line 1020 to
&100. Note the comment in tip #111 about X% being LOCAL.
1000 DEF FNstatus:LOCAL A%,X%,Y%
1010 A%=156:Y%=255
1020 =(USR(&FFF4) AND &1C00) DIV &400