Topcon system 150

Hello.
I'm using Topcon system 150 and I want to start doing VRA. I have a Bogballe spreeder and I want to buy Farmworks Mobile. It is possible to make NMEA output in Topcon's GX-45 console. My question is what do I need more? What I understand is only any computer with 2 DB9 ports? One of it is geting NMEA in and the other gives the signal to spreered's controller. Is that right? Do you offer any hardwere with 2 DB9 ports? I want to be sure that it works ok. Is there any other way to do VRA in my case?