Added a couple of sentences about async acquisition and the

two modes cards do it and then mentioned our new board_info.

diff --git a/doc/tutorial.xml b/doc/tutorial.xml
index 5ca284ec3fd885db2049c613ad9d51bd479699a7..3344d2a4a60096c9f15006a33a650898dd2bc700 100644 (file)
--- a/doc/tutorial.xml
+++ b/doc/tutorial.xml
@@ -132,6 +132,26 @@
       This technique is used in programs such
       as <command>ktimetrace</command> or <command>comedirecord</command>.
     </para>
+    <para>
+      There are two different ways how a sequence of channels is
+      measured during asynchronous acquisition (see also the Figure in
+      the introduction):
+    <itemizedlist>               
+      <listitem>
+       The channels are measured with the help
+       of a multiplexer which switches to the next channel after each measurement.
+       This means that the sampling rate is divided by the number
+       of channels.
+      </listitem>
+      <listitem>
+       The channels are all measured at the same time, for example
+       when every channel has its own converter. In this case the
+       sampling rate need not to be divided by the number of channels.
+      </listitem>
+    </itemizedlist>
+    How your &comedi; device handles the asynchronous acquisition can be found out
+    with the command <command>comedi_board_info -v</command>.
+    </para> 
     <para>
       The program <command>tut3.c</command> demonstrates the
       asynchronous acquisition. The general strategy is always