I know of two methods, each with pros and cons.
1) Actisense adapter plus their NMEA Reader software. I don't recall the cost of the adapter, but maybe $200-$300? You can see an inventory of all the devices on the network, and drill down on individual devices. You can also see a list of all the PGNs (messages) from each device, including how frequently they are being sent. And you can create a trace which is helpful for figuring out interactions between devices. Seeing a list of PGNs and their frequency is great because you can see a full inventory for messages present. But you can't tell the exact order of those messages. Capturing a log lets you then go back and see the exact sequence of messages which is often critical to understanding an interaction.
2) Maretron USB100 or IPG100 plus their N2KAnalyze software. Cost is again $200-$300. N2KAnalyse also shows an inventory of devices, and you cna then drill down on any one looking at specific info as well as what messages are sent from each. But it only offers a list of messages that are being sent from each device. You can open up each message and see the data flash by. But there is no provision to capture a trace and examine a specific sequence of messages.
That said, I use N2KAnalyse at least 10 times for every time I use Actisense. I think part of it is reflective of greater familiarity with Maretron, but it also reflects how often a sequential trace has been needed. But when you need that trace, you need it, and it has been vital to nailing down which device is misbehaving, and what it is doing wrong. Unfortunately most vendors just ignore such problem when you report them, but a few do pay attention and fix their issues. For the other devices that haven't been fixed, I have just dumped them and don't recommend them anymore.