How to detect cFP-1804

[volker_sbk]

Hi,

I have a cFP1804 connected to a cFP2120 via EThernet.  The cFP1804 has a thermocouple module installed which is read once a second by the 2120 using the 'FP Read.vi' (see attached file). When the systems are connected to each other, the 'FP read' returns proper values. When disconnecting the cFP1804, the 'FP read' will still continue to serve cashed values but raise error 33800 until the connection has been re-established. So far so good.

The problem I am having occurs when resetting the cFP2120 while the cFP1804 is offline. At that point a single 'FP read.vi' will cause the program running on the cFP2120 to stall completely.

Any idea how to get around this?

I am using Labview 8.2.1 with RT version 5.0.1

Thanks,

V

[DiscoBall]

Hi Volker,

Are you running your VI on the cFP 2120 or on your computer? When it hangs, do you get any errors? Also, do other loops continue execution indicating that only the FP Read VI has stalled? KnowledgeBase 2FT7TI9O What Happens if FP Read is Called and the FieldPoint Network Module is Offlin...indicates that network errors are considered fatal. So if the cFP 2120 doesn't detect a cFP 1804 this could be causing the VI to hang.

Please let me know if other loops continue execution.

 If possible, could you upgrade to the latest FieldPoint 6.0.4 drivers?

[volker_sbk]

Joshua,

"Are you running your VI on the cFP 2120 or on your computer? Also, do other loops continue execution indicating that only the FP Read VI has stalled?"

Building a startup executable from a slightly modified vi and running it on the cFP2120 produces the same results. Starting the controller while the cFP1804 was offline will not only result in the crash of the vi but also of the cFP2120 as I can't communicate with it from that point onward until reset. There are no error codes returned when this happens.

It seemed to me that the knowledgebase article was suggesting that even though this vi would hang, other vi's would keep executing, which is not the case.

Do you know of any way to ping the cFP1804 at the start of the vi in order to ensure it is on the network before attempting to read from it?

Btw, unfortunately, I am not able to upgrade to the latest field point drivers.

Thanks,

Volker

[DiscoBall · Accepted solution]

Hi Volker,

You can detect RT and Network Targets using the System Replication VI's. An explanation can be found at NI Developer Zone Tutorial: Real-Time Target System Replication at http://zone.ni.com/devzone/cda/tut/p/id/3937. The download link is at the bottom of  the page. Be sure to read the included Read Me for installation instructions. If you run the Find All Targets VI, you will be able to test if the cFP-1804 is on the network.

[volker_sbk]

Thanks for pointing me into the right direction. The 'Find All Targets. vi" works like a charm.

Volker.