Power off before swapping EtherCAT hardware?

Question

NI has provided the ScanEngine API to allows user's the ability to discover C-series and EtherCAT chassis dynamically and I really like it. This allows me to "hot swap" hardware and my software can just adapt dynamically based on the discovered modules. Is turning off my etherCAT chassis prior to doing this recommended anywhere?
In otherwords, I like the idea of putting the ScanEngine in Configuration Mode then pulling out C-series modules and replacing them with new ones without powering off the chassis. Could this potentially harm my hardware? Does NI strictly advise against this?
Thanks,
Craig

Answer 1

Hi Craig,
NI CompactRIO is a small rugged industrial control and acquisition system, and all the NI C-Series modules used in this system are hot-swappable industrial I/O modules. That’s being said, when using a CompactRIO (no matter it’s a cRIO controller or an expansion backplane like NI 9144 EtherCAT slave chassis) with modules in the slots, it is NOT necessary to power down the device.  CompactRIO was designed with this feature in mind.
A slight deference a CompactRIO RT Controller (e.g. NI 9074) and NI 9144 is that, when you swap (even an identical) C-Series IO module on NI 9144, the slave device will report an emergency data to your host system, which might disturb your system if it’s running. The emergency will disappear when you manually or programmatically switch Scan Engine to Active Mode again. But anyhow, this is all for software side; it will not harm your hardware.
Hope it answers your question!
Josiane Zhou
NI-IndComm for EtherCAT