generate low frequency square signal via analog output

[desduen]

hello all
i am new at labview and DAQ devices. i am working on project where using an electro-hydraulic servo system. i want to control the position of the hydraulic cylinder by means of controlling proportional hydraulic valve.i need to control the cylinder to extend and retract continuously. to do that, i need to give command signal (voltage) to the proportional valve with pattern like the attached picture, actually it is similar to PWM signal.

i am using Labview connected with NI-USB 6251. how to generate signal with pattern like the attached picture? i am trying to use Square signal on Simulate signal express VI, but when i set to the low frequency ( 0.1 Hz) , i got error message that "the buffer size is too small". im trying to change the buffer size but error still happened.  i can generate it via counter output, but i need to generate it via analog output.

thanks for your help guys.

[Tepig]

How about using Counter Output?

[crossrulz]

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desduen wrote: i am trying to use Square signal on Simulate signal express VI, but when i set to the low frequency ( 0.1 Hz) , i got error message that "the buffer size is too small". im trying to change the buffer size but error still happened.

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Lower your sample rate.  With this low of an output frequency, 100S/s should be plenty.  Alternatively, use the Square Waveform.vi.

[desduen]

thanks guys for your help.

i am trying to imply solution from crossrulz with my NI-USB 6251 as picture below :

it seems well on waveform chart, but when i try to connect NI-USB 6251 with oscilloscope to see the generated signal, i got the signal generated at constant 7 Volt. it never goes to 0 Volt. i wonder where is the mistake?

i set the DAQ Assistant as pict below :

thanks for your help