diff --git a/Ccs/ccs_function_lib.py b/Ccs/ccs_function_lib.py
index f7a21512fdb2a34545a8125d940299afabef0dc6..d00b77a3c8e533549ee7d746a945d8e3e202acd2 100644
--- a/Ccs/ccs_function_lib.py
+++ b/Ccs/ccs_function_lib.py
@@ -1042,6 +1042,13 @@ def Tcdata(tm):
     dbcon.close()
     tcnames = list({x[1] for x in params})
 
+    # return if no TC can be unambiguously assigned
+    _npars = {x[4] for x in params}
+    if len(tcnames) and len(_npars) > 1:
+        tcdata = None
+        tcnames.append("\n\nAmbiguous packet type - cannot decode.")
+        return tcdata, tcnames
+
     # select one parameter set if IFSW and DBS have entry
     if len(tcnames) > 1:
         params = params[::len(tcnames)]