The key here is PDOs. There will be a way to configure the nodes so that they automatically transmit a CAN message (a PDO) when the spool and rod position and velocity change. All you need to do on the PC side is read these CAN messages and extract the values. They might even do that without any configuration.

Possibly on the simplest level:

1. Send an NMT message setting all nodes to "operational" - this will start the transmission of PDOs.
2. Read the PDOs and extract the data.

On top of that you can add more functionality such as writing values to the nodes using SDOs. If you need SDOs then I would recommend you purchase a library for your PC that handles this for you. Typically LabView can access DLLs as well.

Note that CAN is very simple. It is the software-based protocols that sit on top of CAN, such as CANopen, that can be complex. When reading the specs you should find that only a very small set of functionality is actually mandatory.

Andy