Hey Tony,
There are two hardware methods to interact with NI switch modules: scanning and immediate mode.
In scanning mode, we're downloading a predefined list to the onboard memory of the switch module. Then, whenever the module receives a trigger, it'll advance to the next entry in the scan list. The goal of the scanning design is to offload the switching task solely to the switch module, thus making the scanning process faster and controllable with external equipment. We do allow users to send a software trigger, which allows us to bring the controller back into the picture, but we don't allow the controller to look into the switch state for two reasons: 1 this would slow the switch down, and 2 by the time the OS receives the current switch state, it's possible that the switch module has received a trigger and thus advanced to the next position, thus allowing the controller to make decisions based on potentially out-of-date data.
If you want to continue using scanning mode, you could parse the scan list using the scan list entry syntax and create a string array of the scan list. Then, each time you send the software trigger, you could advance a pointer to the next entry in the string array you've generated... but since you're using the software trigger, we can use the switch module in immediate mode (software) instead.
Immediate mode allows us to close/open relays on the switch module with the controller using software calls. It also allows us to read the relay position using either the associated vis or the Switch soft front panel. There's a great example in the NI Example Finder (LabVIEW»Help»Find Examples) Hardware Input and Output»Modular Instruments»NI-Switch»niSwitch Making Connections on a Switch.
Let us know if I missed something. Have a great day!
-John Sullivan
Problem Solver
