Solution:

Yes, you can change (unipolar - bipolar) during program. Please have a look at structure "PT_AIConfig". There's a property 'DasGain'. You just need to adjust this property before get AI voltage. Following information just for your reference. ================================================================== configure input range AiConfig.DasChan = 0 ?'channel: 0 AiConfig.DasGain = 0 ?'gain code: 0 <== Just change the GAIN code here ErrCde = DRV_AIConfig(DeviceHandle, AiConfig); If (ErrCde <> 0) Then DRV_GetErrorMessage ErrCde, szErrMsg Response = MsgBox(szErrMsg, vbOKOnly, 'Error!!? Exit Sub End If ==================================================================