I have a cellular modem and it just works fine in CR800 using the RS232 port of CR800.
When I tried it with CR800 I just managed it to work when I used full RS232 interface, it just doesn't work using only the TX/RX pair. So I'm facing the same issue with CR6, but CR6 has no RS232 port.
Do I need a converter to use CPI/RJ45/RS232 port with a DB-9 connector or just a cable RJ45<>DB9 works?