Non-volatile memory on cRIO

[kkonline]

I am using a cRIO 9072 in combination with a TPC 2106 as HMI in an industrial process control environment.
The embedded program on the cRIO gets its variable process control parameters like Set Point, PID Gains, Control limits etc. from the HMI through shared variables.

The system works fine, until there is a problem with the network or TPC. If the Ethernet connection to the TPC fails, or if the TPC is switched off (due to any reason - like power fail, ethernet switch failure, network cable fault etc.,) the entire process goes for a spin as all the control parameters are lost.

I would appreciate if somebody can suggest ways for the following:

1. Store these control values in the non-volatile memory of the cRIO as and when it is updated on the TPC.
2. The cRIO Real time host program should read values directly from the non-volatile memory of the cRIO 9072.
3. Even if the HMI (TPC 2106) is switched off, the cRIO Real time program reads the the last entered value.
4. When the HMI is switched ON, it should retain the last held values and not default values.

Please note the following:
At any given point of time the TPC will write and the cRIO should read the data - i.e. two separate sources (RT program and TPC program) will access the same data at any point of time.

Thanks

KRISH

[AdnanZ]

It's possible to do what you are looking for. What have you implemented so far?

Message Edited by Adnan Z on 04-06-2009 02:11 PM

[jkurtw]

This example implements most of your requirements.

http://decibel.ni.com/content/docs/DOC-4134

The shared variables are hosted on the cRIO controller and since shared variables get stored in non-volitale memory, including their last value, you will get the behavior you are looking for.

In the initialization step in the HMI code, you will need to write the shared variable values to the local variables of your HMI controls, and then you will have the behavior you described (HMI takes on last values written to RT, not default values).

Kurt