LMS 522 NMEA 0183 Problem

[billro]

I have two Lowrance 522s. One of them is connected to a LGC 3000 GPS puck due to the sometimes unreliable performance 522's internal GPS antenna. I'm trying to connect the two 522s together using the NMEA 0183 connection to send the more reliable GPS data from the 522/LGC3000 unit to the other 522.
I can't seem to make it work. As far as I can tell I have it connected correctly and the units configured properly.

I hooked a laptop PC to the serial connection and I can see that the 522/LGC3000 unit is transmitting the data, but the other unit won't receive. It says "Waiting for NMEA serial data".
I called Lowrance. The tech wasn't much help. He told me he would e-mail me a 'networking troubleshooting guide'. I haven't received it yet. Guess I'll have to call again.

I may just give up and purchase the necessary hardware to use a NMEA 2000 connection instead. I was just trying to save a few dollars.

Has anyone had sucess with a similar setup?