Labview interfacing with NI cDAQ-9172

Question

I currently have access to a NI cDAQ-9172 with a NI-9205 AI input
board and a NI-9481 relay control board. I basically have the DAQ
Assist tools for the analog inputs and the relay outputs, however, I'm
having trouble interfacing them together, such as if the two analog
outputs are above x Volts, turn on the relay control; otherwise, turn
it off. Do I need to create a task for a specific DAQ Assist tool in
order to control the behaviour of the relay outputs based on the
analog inputs?

Answer 1

Hello Stanley,
Let me try to address your questions in order:
1. LabVIEW gives you the ability to program several design patterns
including Finite State Machine, Master/Slave and Producer Consumer.
LabVIEW even provides templates for these design patterns, which you
can create by going to the File menu and selecting New.... The image below shows where you can select from the different design pattern templates.
For more information about the state machine design pattern specifically, I would recommend that you examine this tutorial.
2. I believe the "DAQmx Tools" you referred to are the DAQmx sub-VIs in
the DAQmx sub-palette. You must use the inputs (controls) and outputs
(indicators) to configure these VIs, there is no pop-up menu like there
is for the DAQ Assistant. However, you are able to generate the sub-VIs
from a configured DAQ assistant using the right-click menu, as shown in
the diagram below. This would allow you to configure your NI-DAQmx operation with the pop-up window, and then optimize performance using the DAQmx sub-VIs.
3. Based on the description of your application, I would strongly
suggest that you consider either the state machine template discussed
above or the NI LabVIEW Statechart Module. This module is designed to
give you a higher level of abstraction for complex systems. Since you
already have a flow chart, it seems that it would be pretty easy to
convert that to a statechart to programmatically implement it. You can
see a video here on how to implement state machines in the LabVIEW Statechart Module.
If you have questions about how to architect your program specifically,
I would recommend that you post to a new forum. You are more likely to
get better insight and more relevant information on that topic if you
post a new question that reflects the appropriate topic.
Message Edited by Matt A on 09-17-2007 07:37 PM
Matt Anderson
Hardware Services Marketing Manager
National Instruments
Attachments:
Generate NI-DAQmx Code.JPG ‏16 KB
Design Patterns.JPG ‏73 KB