I am trying to run r.water.outlet by PyQGIS but getting grass folder not configured error
I have QGIS 2.18 installed and Grass is not installed on windows 10 and I am able to use r.water.outlet from Processing>Toolbox>r.water.outlet but getting error for using it by PyQGIS below code
from qgis.core import *
from PyQt4.QtGui import *
import processing
registry = QgsMapLayerRegistry.instance()
watershedLayer =registry.mapLayersByName('Gondala_AET-PET')[0]
xmin = watershedLayer.extent().xMinimum()
xmax = watershedLayer.extent().xMaximum()
ymin = watershedLayer.extent().yMinimum()
ymax = watershedLayer.extent().yMaximum()
processing.runalg('grass:r.water.outlet', 'Drainage direction' , 695991.202933 , 2180877.920948 ,"%f,%f,%f,%f"% (xmin, xmax, ymin, ymax),
0.0,'b') # 'Drainage direction' is layer name in layer panel
Below is window pop up after running this script.