Another option to confuse you on outputting strings.
This uses a record length method, so that anything can be transmitted including null.

fin: mov dptr,#recfh ;transmit the old flow header
mov r1,#recfhe ;with a length of whatever
call putstrn
keep going:------

putstrn:
clr a
movc a,@a+dptr ;get the char
jnb ti,$ ;transmit it, if the buffers empty
mov sbuf,a
inc dptr ;point to the next char
djnz r1,putstrn ;loop thru all char
ret

; Old protocol header for flow
recfh: db 02h,0dh,0ah,'FLWEX',00h,20h,'='
recfhe equ $ - recfh
;
Lets tear this one up.
Have fun,