diff -r 8d1cc99a8f54 -r 095c73591b7e controls/DebugVariablePanel/RingBuffer.py
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/controls/DebugVariablePanel/RingBuffer.py	Mon Jun 14 16:48:39 2021 +0200
@@ -0,0 +1,55 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+# This file is part of Beremiz
+# Copyright (C) 2021: Edouard TISSERANT
+#
+# See COPYING file for copyrights details.
+
+# Based on Eelco Hoogendoorn stackoverflow answer about RingBuffer with numpy
+
+import numpy as np
+
+
+class RingBuffer(object):
+    def __init__(self, width=None, size=65536, padding=None):
+        self.size = size
+        self.padding = size if padding is None else padding
+        shape = (self.size+self.padding,)
+        if width :
+            shape += (width,)
+        self.buffer = np.zeros(shape)
+        self.counter = 0
+        self.full = False
+
+    def append(self, data):
+        """this is an O(n) operation"""
+        data = data[-self.padding:]
+        n = len(data)
+        if self.remaining < n: self.compact()
+        self.buffer[self.counter+self.size:][:n] = data
+        self.counter += n
+
+    @property
+    def count(self):
+        return self.counter if not self.full else self.size
+
+    @property
+    def remaining(self):
+        return self.padding-self.counter
+
+    @property
+    def view(self):
+        """this is always an O(1) operation"""
+        return self.buffer[self.counter:][:self.size]
+
+    def compact(self):
+        """
+        note: only when this function is called, is an O(size) performance hit incurred,
+        and this cost is amortized over the whole padding space
+        """
+        print 'compacting'
+        self.buffer[:self.size] = self.view
+        self.counter = 0
+        self.full = True
+