Brief tutorial on a null modems:

In the Nevo serial module, the male connector has a pin layout such that Pin2 transmits data (Tx), and Pin3 receives data (Rx). Pin5 is always ground. Now, in most devices that have a female RS232 chassis connector, the pin layout is is the opposite, such that Pin2 receives data (Rx) and Pin3 transmits data (Tx). If you think about it, this is what you need- Pin2 on the Nevo connector TRANSMITS data, so it needs to meet up with a pin on your device that RECEIVES data. That's why you can pretty much plug-and-go when the component has one of these female connectors.

If, however, the component has a male connector just like the Nevo module, you have two potential issues. First of course, you need a male-to-male adapter, also called a gender changer. But since those male connectors tend to have the same pin layout as the Nevo module, expecting to TRANSMIT on Pin2 and RECEIVE on Pin3, you need to swap these in your adapter or cable.

This is what is called a null modem. It can be just a little adapter, or it can be a cable, but the point is that it internally reverses those pins so they "meet up" right between the two things you're connecting, allowing them to talk to each other.


So that's the skinny on null modems. I'll take a look at the Sony documentation a little later and see what I can discern about it. (How lame that they don't make the info readily available....you have to be "authorized?" Geez, Sony, how....1980s.)