Direct communication between 2 cRIO controllers

[jdenn]

I have an application where I am using a NI-9030 and NI-9035 controller and I need to pass critical I/O data from 9030 to the 9035.  The controllers are separated by a distance that is near the distance limits of Ethernet (greater than 350 ft).  For reliability reaons, I would like to communicate the data between the controllers using the FPGA and not the Real Time Target.

1.) Is RS-485 my only option that is natively supported by Labview?

2.) Is there a quick/easy way to develop communications between the CRIOs using on the FPGA interface, where one controller is master and the other is slave?  All of the example code I've seen looks like it runs off the RT target.  One way seems to use DSC and sets up a Modbus I/O server, but again that looks like it runs on the RT target.

3.) From what I understand, the default RS-485 inputs on both of the controllers are only accessible through the RT application.  Is there a way for the FPGA to access these inputs directly without having to interface with the RT target?  Or is it required to use a NI-9871 module on both CRIO?

Any information that could at least just point me in the right direction would be appreciated.  Thanks.

[a_clucker]

Hey jdenn,

1. Check out the "Industrial Communication" section of the NI C Series Module Compatibility Chart. CAN, CANopen, DeviceNET, ASi, HART, and PROFIBUS are all supported via FPGA programming, in addition to serial. There are probably more options enabled by products on the LabVIEW Tools Network.

2. Of the protocols I listed, serial, CAN, and PROFIBUS can do bi-directional communication on cRIO. PROFIBUS protocol has a defined master/slave structure, whereas CAN and serial do not define that (but many CAN / serial devices are developed to act in a 'slave'/'server' fashion and respond to requests/queries)

3. See the White Paper I linked above. You can program the 9871 in FPGA. They are a little different to program I/O compared to other FPGA modules; see KB 4YM9N3UV. The online help is also describes methods and properties available.