Making Things Talk

LOOK, MA, NO COMPUTER! 139

Serial-to-Ethernet Modules: Programming

and Troubleshooting Tools

You probably hit a number of problems in making the connections in the last section.

Perhaps you wired the transmit and receive connections backwards, or perhaps you got

the IP configuration wrong. Probably the most challenging thing about troubleshooting

your problems was that there was no clear indication from the Micro module that

anything had happened at all. This is the norm when you’re working with these modules,

or with just about any embedded modem-style module that you build yourself. This

section covers a few things you should always check, and a few tools that will help you

solve problems. These principles apply whether you’re using the Lantronix modules or

some other embedded network module.

The Three Most Common Mistakes

Power and Ground

Always check whether you have made the power and

ground connections correctly. If you’re lucky, the module

you’re using will have indicator LEDs that light up when

it’s working properly. Whether it does or not, check the

voltage between power and ground with a meter to make

sure you’ve got it powered correctly.

Transmit and Receive

Confirm that you’ve got the module’s transmit pin wired to

the receive pin of your serial port or microcontroller, and

vice versa. If you don’t, you’ll get nothing either way.

Configuration

If you’re sure about the hardw ...