Error: using an node in place of an refnum

[SophieJS]

Hi, I have a basic question. I connected 2 terminals of the same type (FPGA I/O), however, I am getting an error (I attached a screen picture). The source is an FPGA I/O Out from a node and the sink is FPGA I/O input of an FPGA Read/Write.vi. The terminals are of the same type; why am I getting an error? Connecting a refnum to the vi does not cause an error. Why?

[Chris.N]

FPGA Read/Write.vi is not a VI that is part of LabVIEW, can you please show what code is in that subVI?  

[nathand]

My guess is there's some difference or incompatibility between the two types of digital IO such that you can't connect them.  If you change the IO node (or the reference) so that they both refer to the same output, or at least different outputs on the same module, can you connect them?

EDIT: you may also find it enlightening to open the FPGA Read Write VI and right-click on the FPGA IO control on the front panel.  Look at the Configure IO Type menu item.  It may be that one of the digital IOs does not support some method that terminal is configured to support, which could lead to a wire conflict, I think.

EDIT 2: see "Configuring the FPGA I/O Node Name Control (FPGA Module)" in the LabVIEW FPGA Module help.

[SophieJS]

I downloaded this project from ni.com (from here: http://zone.ni.com/devzone/cda/epd/p/id/2164). It is for serial read/write via an RS-232.

My question is this: in the main.vi (shown below)  input1 to the FPGA Read Write.vi is a reference (reference Port8/DIO0 in the example). If I replace the reference by a node, I get an error (I see a broken arrow and a broken wire even though the type of the sink and source are the same). Why is this?  

[nathand · Accepted solution]

The problem is not the node versus refnum, it's the channel that you selected.  In the image in your initial post, you show the IO Node referencing Module1/DIO2 and the refnum referencing Port8/DIO0.  Those channels may not support the same set of methods.  According to Configuring the FPGA I/O Node Name Control (FPGA Module) (sorry for the broken link in the previous post), "When you use an FPGA I/O control as an input on a subVI, the input accepts only I/O items that support a superset of the methods and properties you enable for the FPGA I/O control."  You can configure which properties are needed by right-clicking on the control on the subVI's front panel and choosing "Configure IO Type."  If you eliminate the methods or properties that are supported only by Port8/DIO0, you should be able to connect Module1/DIO2 successfully even from an IO Node.

[SophieJS]

Thank you.

[nathand]

Kudos are of course always appreciated, but you might also click the "Accept as Solution" on the appropriate message to mark the thread as resolved.