how to acquire the synchronized signal?

[xingwangcqu]

we are use the open ephys system to acuquire the multichannel neuronal cells of animals when the acoustic stimuli is broadcasted. In order to analyze the evoked response, we need acquire the synchronized signal of the acoustic stimuli.
But it doesn't work when we connected the analog input signal to the hardware of the "open ephys", the computer cannot detect the synchronized stimuli. Would you like to help me find the solution method?

the input synchronized stimuli is between 0-3v. But we can see nothing on the destination channel.

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