When ever it is required Null modem wired cable for your instrument RS232 port, now there is also available and MINI Null modem DB9 connector!
The RS-232C port connector this has become unpopular as default option to recent made laptops and PC.
Modern RS-232C to USB kits gained popularity, but vast majority of them this missing Null modem configuration at the RS232 side of them.
Now lets measure the available options:
a) An NEW Null modem configured cable.
b) Modern RS-232C to USB kit this now requiring also option a)
c) Modern RS-232C to USB kit this now has the choice to use MINI Null modem DB9 connector instead.
I do not think that sort lengths of Null modem configured cable, they are causing performance loss at RS232 communication.
Either way if you do care to eliminate unwanted cable length, then there is no better choice than using Mini null modem instead.
I made the choice of getting from eBay the DB9 female to female, if you are wise thinking consumer then never spend more than €2.20 EUR (shipping included) about it.