Multiple DAQ Assistant Speed Issues

[trollerson]

Hello!

Quick project description and overview

For the last couple of months I have been working on a gas turbine engine simulator project using LabView. I need to generate both and digital outputs as well as acquire analog and digital inputs. We will be using the program as a test device to make sure the control system (CS) is functioning for controlling the real engine. The basic logic of the program is take in input data, calculate new values, update outputs.  While the gathering of data and calculating new values I need the hardware to continue outputting the previous values so the CS does not think the engine is in the process of blowing up. Also, I’m not sure if it would be relevant but, I am currently running LabView 8.0 but will be upgrading to the latest version at the end of the week. I am using the cDAQ-9172 chassis and assorted modules. Right now, I’m sending some signals in the office to the device to simulate a start-up and timing to the inputs. In the final version I will be looking at having 9 DAQ assistants one per module.

Primary Issue

When I began to test the program with hardware last week it went from running about 40-50 times a second down to 3-4 times a second (Using N samples). I need to get the speed back up as much as possible so the program can respond faster and more accurately to the inputs. A month ago I did a small test of the programs analog outputs with the CS with only one DAQ assistant in continuous output mode. It was able to run fast enough. Now when I try to use multiple DAQ Assistants continuously I get the error 50103 (The specified resource is reserved). 

Questions

How can I run Multiple DAQ assistants and maintain a fast program speed?

What setting for the DAQ assistants are best? N Samples? Continuous? 1 sample on demand? One sample hardware timed?

Would using lower level DAQ speed up the program?

Any help is much appreciated! Thanks!

trollerson

[Dennis_Knutson]

You can't run multiple DAQ Assistants with the same type of task (i.e. analog input) and a simple search of '50103' would explain the reason why. The max sample rate is going to depend on the modules you have and you have not provided that list.

[trollerson]

Ahhhhh I see now.  All analog inputs need to be under the same DAQ assistant.  I was under the impression that all modules had to have their own DAQ Assistant.  The error appears to have resolved now that I have put all of the digital and analog inputs and outputs into the same DAQ assistants.  And the voltages have stabalized as well!  They were doing a little bouncing act before.  After combating a few other error its now running around 23 updates per second.  I'm just trying to make the buffer larger so I can get rid of 200279. 

Thanks for the help Dennis!

Modules I have:

NI 9421  (Digital input)

NI 9205  (Analog Voltage Input)

NI 9263  (Analog Voltage Output)

NI 9265  (Analog Current )

NI 9203  (Analog Current Input)

NI 9472  (Digital output)

NI 9481  (Digital relay)

NI 9269  (Analog voltage output)

NI 9227  (Analog current input)