Tool for request data from PI Processbook
Usage:
from pypiprocessbook import PI
pi = PI("server_name")
results = pi.read("tag") # get the last value for the tag
results = pi.read("tag", start_time) # get the value for the tag at specified datetime
results = pi.read("tag", start_time, end_time, interval) # get the values for the tag at specified datetime interval every 'interval' minutes