frappy_psi.bkpower: improve doc

Change-Id: I0736d1d8a40b0140bfdbf5aca189b8ddc5b22973

frappy_psi/bkpower.py

@@ -17,10 +17,39 @@
 #   Markus Zolliker <markus.zolliker@psi.ch>
 #   Jael Celia Lorenzana <jael-celia.lorenzana@psi.ch>
 # *****************************************************************************
-"""Powersupply B&K Precision BK168xB"""
+"""Powersupply B&K Precision BK168xB
+
+The following lines are part of a config file for the  frappy-server process
+The frappy server creates the following modules and refreshes the values with a refresh rate  of 1 sec.
+The communication with the powersupply is established via serial over USB.
+The manual can be found here  https://www.vectortechnologies.gr/images/products/2022/02/168xB_programming_manual.pdf
+
+Mod('htr_io',
+    'frappy_psi.bkpower.IO',
+    'powersupply communicator',
+    uri = 'serial:///dev/ttyUSBupper',
+   )
+
+Mod('htr',
+    'frappy_psi.bkpower.Power',
+    'heater power',
+    io= 'htr_io',
+   )
+
+Mod('out',
+    'frappy_psi.bkpower.Output',
+    'heater output',
+    io = 'htr_io',
+    maxvolt = 50,
+    maxcurrent = 2,
+   )
+"""
+
 
 from frappy.core import StringIO, Readable, Parameter, FloatRange, Writable, HasIO, BoolType
 
+
+# define the IO class
 class IO(StringIO):
     end_of_line = ('OK\r', '\r')
     default_settings = {'baudrate': 9600}