Looking for architecture suggestions to support communications with Field Point based LV-RT applications.

[Ben]

I am developing the design of an application that will monitor the status of a large number (1-50, with options to expand to 1000) Compact Field Point units that will be running an LV-RT that I will also be developing.

I think a LV2 global (on the RT platform) that is updated by the LV-RT app and read by the Windows app (usaing VI server) would work well but I am open to ideas.

The throughput should not be extreme. I only need to know about deadband changes or alarms that should amount to about one update every couple of seconds.

Does anyone have any suggestions regarding;

1) Detecting Time outs?

2) Retrying and reconnecting?

All thoughts and ideas
are welcome!

Ben

[Aaron_G]

Ben,

One easy option is to use the Publish Data.vi in the cFP-20xx series controllers to publish the data that you want made available to the server. There are several advantages to this approach:
1) Any computer that has FieldPoint Explorer can subscribe/read all the data. These data points will show up under the cFP-20xx controller (after app is running).
2) This data can in turn be published to other applications and other computers via the FieldPoint OPC Server.
3) Applications that use DataSockets on Windows based machines, can use the DataSocket/Lookout Protocol to directly subscribe to this data.
4) The NI Lookout protocol automatically handles timeouts and re-subscribe attempts for you.
5) The NI Lookout protocol is designed to minimize network
traffic and only publishes data as it changes.
6) When publishing items, you are able to provide two levels of hierarchy names, thus you could easily create separate groups for alarms, deadbands, etc...

Regards.
Aaron

[Ben]

Hi Aaron,

I've taken a look at this previously over-looked VI. It looks rather intersting.

THanks for pointing it out to me. I did not notice it before now.

Ben

[Ben]

I just tried to experiment with that VI.

Is that a VI that will only run on the RT target?

I get an error trying to create a read-write Item. The error says memory error.

Ben

[Aaron_G]

Yes, the Data Publish.vi only works when embedded into the controller.

Regards,
Aaron