you can't refer to ascii to do your stuff.

if (PLS <153) AND (PLS> 143) then
rled =0
lled = 0
endif
if pls > then 153 then lled = 1
if PLS < 143 then rled = 1

this already work as you wish.

you can also refer to binary
if (PLS <%10011001) AND (PLS> %10001111) then
rled =0
lled = 0
endif
if pls > then %10011001 then lled = 1
if PLS < %10001111 then rled = 1

Or in hexadecimal
if (PLS <$99) AND (PLS> $8F) then
rled =0
lled = 0
endif
if pls > then $99 then lled = 1
if PLS < $8F then rled = 1


If you want to receive value from PC and convert it to decimal
SERIN2 PORTB.0,16780,[dec3 loop]

this will receive 3 character and convert it to decimal value from your terminal.

If you want to send 123 to pic type 123, if you want to send 10 type 010 and that's it