I checked the web site of NI. I found that the Compact feildpoint is not expandable if the number of modules is over than 8. If we need more than 8 modules, we will need multiple systems. So, I want to know if the feildpoint can handle over than 8 modules.
No, Compact FieldPoint systems can not have more than 8 IO modules per controller. Traditional FieldPoint systems can have up to 9 IO modules per controller.
I think you could expand the fieldpoint system by adding more modules connected to an NI-FP-1601 module. In your code you would use the Feildpoint VIs and just use the TCPIP address of the remote expansion modules.
you probably could not rely on the speed but with a good network it should be OK
You can indeed use any of the ethernet controllers to add connectivity over a network, but the limitation of 9 modules per FieldPoint controller or 8 modules per Compact FieldPoint controller will still govern your operation.