Scan Engine mode on RT not working with EtherCAT chassis NI-9144

[JanBarton]

Hi,

I have problem with communication of RT cRIO-9074 with NI-9144 via EtherCAT.
I have add the expansion chassis with one NI-9203 module to my system running on cRIO-9074.
I am using it in scan engine mode. My PC application is communicating with RT by Network Stream. When I run only RT application, the RT is reading I/O variables from EtherCAT chassis without any problems, but when I run the host application on PC, the RT probably goes to configuration mode and stops communicating with EtherCAT chassis - I can see that the LAN LED on extension chassis stops blinking. Then with still running application I click in the LabVIEW project explorer, the target item and select Utilities»Scan Engine Mode»Switch to Configuration and then "Switch to Active" back and it starts communicating. I tried to do the same programmatically with the Set Scan Engine Mode VI but it doesn´t work so in Runt-Time it is not working as well.

The above described behaviour happend when I added the expansion chassis in the project and only the inputs from module place in that chassis are affected, the rest 8 modules placed directly in cRIO-9074 are working withou any problems.

System:

Win7 professional
Labview 2013 SP1
NI-Industrial Communications for EtherCAT 2.7
Ni CompactRIO 13.1

[DStavilaNI]

Hi Jan,

               When setting up the Ethercat system, did you follow the same steps as provided here ? Also, as a first approach, to be sure that the Scan Engine enters the configuration mode at startup, you could try and use the " Get Scan Engine Mode VI " to evaluate its state. This should make the things a bit clearer.

Regards,

Denis

[JanBarton]

Hi Denis,

yes I set it according the tutorial. I can see that the Scan Engine goes to pre-operational state when I start the PC aplication which communicate with RT controler via Network Streams. In LabVIEW I can then change the mode to Active in project while the application is still running and it starts to read out the values from the chassis. It seems that the Network Stream communication is  switching the Scan Engine back to config mode.

BR, Jan

[DStavilaNI]

You could try to use some Flat Sequences and see if it works 

1) create the Network Stream

2) next frame, Set Scan Engine Mode.vi to set it to active mode

3) Get Scan Engine Mode VI - and check if it has changed

4) If it has changed, step to the execution of the rest of the code

But I would recommend to create a project, step bu step, with some small VI's on your host and the Real Time controller just to test this functionallity, to begin with.  

Denis

[JanBarton · Accepted solution]

Hi,

problem solved. The reason was function RT Set Date and TIme.vi which casues error on NI-9144 and blocked EtherCAT communication. I have found that this function is not longer supported in LabVIEW. After deleting this function from RT aplication everything works well. 

BR, Jan