Amount of EtherCAT Devices In A Network

Updated Dec 22, 2022

Reported In


  • NI-9144
  • NI-9145
  • CompactRIO Controller

Issue Details

How many EtherCAT Expansion Chassis (NI 9144 and NI 9145 devices) can I have in my EtherCAT Network using a NI CompactRIO as the master?


The theoretical device limit for an EtherCAT network is 65,535 slaves, and Fast Ethernet (100 Mbit/s) limits are similarly high. The real limiting factor in the maximum number of devices in this system is the number of I/O channels you are deploying, the speed of the controller, and the application you are running.


Refer to the document Expansion I/O for LabVIEW RIO Systems: An In-Depth Comparison for more information.

Additional Information

Note that all chassis in a daisy chain share the same “pipe” or bandwidth back to the host controller when configuring a system and calculating total throughput requirements. Also, loop rate is affected by device count and data on the bus, as each chassis and cable adds latency to the system.


Refer to the document Benchmarks for the NI 9144 EtherCAT Slave Chassis for more information.