Basler Camera User Manual page 230

Features
If the Auto Exposure Time Upper Limit parameter is set to a sufficiently high value
the camera's frame rate can be decreased.
To set the exposure auto function using Basler pylon:
1. Select the Auto Function ROI, for example ROI 1.
2. Set the value of the Offset X, Offset Y, Width, and Height parameters for the ROI.
3. Set the value of the Auto Exposure Time Lower Limit and Auto Exposure Time Upper Limit
parameters.
4. Set the value of the Auto Target Value parameter.
5. Set the value of the Exposure Auto parameter for the "once" or the "continuous" mode of
operation.
You can set the exposure auto function from within your application software by using the pylon API.
The following code snippets illustrate using the API to set the exposure auto function:
// Select auto function ROI 1 (as an example) to allow
// Exposure Auto to control image brightness.
camera.AutoFunctionAOISelector.SetValue
(AutoFunctionAOISelector_AOI1);
camera.AutoFunctionAOIUseBrightness.SetValue(true);
// Set the position and size of the auto function ROI
camera.AutoFunctionAOIOffsetX.SetValue(0);
camera.AutoFunctionAOIOffsetY.SetValue(0);
camera.AutoFunctionAOIWidth.SetValue(1294);
camera.AutoFunctionAOIHeight.SetValue(964);
// Set the maximum possible size of the selected auto function ROI
camera.AutoFunctionAOIOffsetX.SetValue(0);
camera.AutoFunctionAOIOffsetY.SetValue(0);
camera.AutoFunctionAOIWidth.SetValue(
camera.AutoFunctionAOIWidth.GetMax() );
camera.AutoFunctionAOIHeight.SetValue(
camera.AutoFunctionAOIHeight.GetMax() );
// Set the exposure time limits for exposure auto control
camera.AutoExposureTimeLowerLimit.SetValue(1000.0);
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AW00123402000
Basler ace USB 3.0