Giving signal to Analog Output as command signal to control an device connected externally

[Kirit]

I need to use 2 signals(say A & B signals) from 2 Analog Inputs. Then i need to take difference like (A - B) and use this output(Numeric input) as command line signal(voltage) to Analog Output where i need to control a device(relief valve) connected externally.

This relief valve is normally open, so by giving signal, the valve closes proportionally to the signal it is getting from AO channel.

I'm using PCI 6259 & PCI6711 as hardware for my application.

Needed hint of assistance in getting this logic to move to next level.

Thanks for going through this message 

-Kirit

[devchander]

Hello Kirit,

One small clarification I seek, before answering your query

Did I get this part of what you explained correctly?

"

1.You want to measure 'Differential Voltage' on one 'Analog input channel' in Differrential mode or measure the two voltages on two seperate analog Input channels in either differential or single ended mode and then, find their difference

2. Then you want this Voltage value to be generated on the Analog output of your DAQ Card

 "

Now the"use this output(Numeric input) as command line signal(voltage) to Analog Output" part, got me a bit confused.

Are you talking about passing Voltage value as a command line Argument to an Analog output VI?

Hope this helps

Regards,

Dev

Message Edited by devchander on 08-28-2009 12:20 AM

Message Edited by devchander on 08-28-2009 12:20 AM

[Kirit]

Hello Kirit, One small clarification I seek, before answering your query Did I get this part of what you explained correctly? " 1.You want to measure 'Differential Voltage' on one 'Analog input channel' in Differrential mode or measure the two voltages on two seperate analog Input channels in either differential or single ended mode and then, find their difference 2. Then you want this Voltage value to be generated on the Analog output of your DAQ Card " Now the"use this output(Numeric input) as command line signal(voltage) to Analog Output" part, got me a bit confused. Are you talking about passing Voltage value as a command line Argument to an Analog output VI? Hope this helps Regards, Dev

Hello Dev,

Let me try out again,,,,there are 2 tasks

1. I want to generate 2 signals(A & B) from 2 analog input channels. Then i want to subtract(A-B) for both the signals of 2 analog input channels. Lets say C as difference of both signals.

2. Now i want to connect/loop this signal(C) to Analog Output channel , so that i can use this signal as command line signal to the device(relief valve) connected externally.

 I dont know whether this explanation is clear or i will try again

Thanks for the feedback

Regards

Kirit

[devchander]

Hello Kirit,

Here is some things I would suggest you to consider

First, See which is the best way to connect your signals to Analog Input channels

This links will help you in deciding that: Filed Wiring and Noise considerations for analog signals

It must help you decide if you can connect both the signals to one AI channel in differential mode and get the differential Voltage (A-B) value

or you will have to connect them to two AI different channels ( in either Differential or Single ended mode) and subtract one AI value from the other

Then I recommmend you look at Analog Input and Analog output example VIs shipped with Labview

Find examples>>Hardware Input Output>> DAQmx>> Analog measurement>>Voltage folder

Find examples>>Hardware Input Output>> DAQmx>> Analog Generation>>Voltage folder

You may also want to take a look at AI- AO synchronization example VI

Find examples>>Hardware Input Output>> DAQmx>> Synchronization>>Multi Function Folder

From the Hardware that you describe, the PCI 6259 is a Multifunction DAQ card, which has 16 DI/32 SE AI channels and 4 AO channels. This DAQ alone must be enough for your application.

But do read the Card's Device specification and verify if the signals you want to measure and the Device/ Valve you want to drive are compatible with the DAQ card's AI-AO specifications or if you need a suitable customized inteface hardware.

Any further clarifications, please do ask

Regards,

Dev