diff --git a/frappy_psi/cryoltd.py b/frappy_psi/cryoltd.py
index cb7d75f7..8feb7212 100644
--- a/frappy_psi/cryoltd.py
+++ b/frappy_psi/cryoltd.py
@@ -27,7 +27,7 @@ changed from the client is fixed for at least 10 seconds.
 """
 import re
 import time
-from math import copysign
+from math import copysign, sqrt
 from frappy.core import HasIO, StringIO, Readable, Drivable, Parameter, Command, \
     Module, Property, Attached, Enum, IDLE, BUSY, ERROR, nopoll, PersistentParam, \
     PersistentMixin
@@ -624,3 +624,15 @@ class Compressor(Channel, Drivable):
         """reset error"""
         self.sendcmd('Set:Compressor:Reset <CH>')
         self._error_text = ''
+
+
+'''
+class Absfield(Readable):
+    main = Attached()
+    bx = Attached()
+    by = Attached()
+    bz = Attached()
+
+    def read_value(self):
+        return sqrt((self.main + self.bz) ** 2 + self.by ** 2 + self.bx ** 2)
+'''