Dear,
“You can connect to PC serial port directly first.” I mean that you just let the GPS connect to USB port. I use it with seeedstudio.com/depot/uartsb … ?cPath=109. This UartSB to plug on and via USB to PC. I’m not sure your MAX232 can do that?
seeedstudio.com/depot/datash … -MS5-07025.pdf
This is document for the GPS. You can refer to.
You also can search “$GPTXT”. This message transfers various information on the receiver, such as power-up screen, software version etc. And Google can help you know more GPS protocol.
And on my PC I use U-center directly work with GPS. You can try it first.
Good Luck
Yuri