diff --git a/docs/setup.html b/docs/setup.html
index b8f1f3a..2d909f7 100644
--- a/docs/setup.html
+++ b/docs/setup.html
@@ -385,35 +385,45 @@ <h2>5. Debug and Error Messages</h2>
 Generation of debug and error messages is controlled with two shell variables,
 <code>streamDebug</code> and <code>streamError</code>.
 Setting those variables to 1 (actually to any number but 0) enables the
-messages.
+messages. A few noisy and rarely useful debug messages are only enabled when
+setting <code>streamDebug</code> to 2.
 Per default debug messages are switched off and error messages are switched on.
 Errors occuring while loading protocol files are always shown.
 </p>
 <p>
-Warning: Enabling debug messages can create a lot of output!
-At the moment, there is no way to set filters on debug or error messages.
+Warning: Enabling debug messages this way can create a lot of output!
+Therefore, some limited debugging can be enabled per record, independent of
+the <code>streamDebug</code> variable using the <code>.TPRO</code> field of
+the record. Currently, setting <code>.TPRO</code> to 1 or 2 enables some
+basic information about the processing of a record and its i/o.
 </p>
 <p>
 Debug output can be redirected to a file with the command
 <code>streamSetLogfile("<var>filename</var>")</code>.
-When called without a filename, debug output is directed back
-to the console.
+If the file already exists, it will be overwritten, not appended to.
+While debug messages are only written to the defined log file, error messages
+are still printed to <var>stderr</var> too.
+Calling <code>streamSetLogfile</code> without a filename directs debug output
+back to <var>stderr</var> and closes the log file.
 </p>
 <p>
-By default the debug/error output is set to be colored if the terminal allows
-it but this can be set to always colored or never colored by setting 
-<code>streamDebugColored</code> to 1 or 0 respectively.
+By default, error messages to the console are printed in red color if
+<var>stderr</var> is a tty at startup time, using ANSI color codes. Some
+terminals may not support this properly.
+The variable <code>streamDebugColored</code> can be set to 0 or 1 to
+disable or enable colored error messages explicitly.
+Error messages written to a log file do not use colors.
 </p>
 <p>
 Error and debug messages are prefixed with a time stamp unless the variable
 <code>streamMsgTimeStamped</code> is set to 0.
 </p>
 <p>
-When a device is disconnected StreamDevice can produce many repeated timeout 
-messages. To reduce this logging you can set <code>streamErrorDeadTime</code>
-to an integer number of seconds. When this is set repeated timeout messages 
-will not be printed in the specified dead time after the last message. The 
-default dead time is 0, resulting in every message being printed.
+when a device is unresponsive, StreamDevice may produce many repeated timeout 
+messages. To reduce this, you can set <code>streamErrorDeadTime</code>
+to an integer number of seconds. In this case, repeated timeout messages 
+will not be printed during the specified dead time after the last printed
+message. The default dead time is 0, resulting in every message being printed.
 </p>
 
 <h3>Example (vxWorks):</h3>
diff --git a/src/StreamCore.cc b/src/StreamCore.cc
index e9dfd11..1a88cf8 100644
--- a/src/StreamCore.cc
+++ b/src/StreamCore.cc
@@ -603,6 +603,7 @@ evalOut()
     // flush all unread input
     unparsedInput = false;
     inputBuffer.clear();
+    inputLine.clear();
     if (!formatOutput())
     {
         finishProtocol(FormatError);
@@ -1011,6 +1012,7 @@ readCallback(StreamIoStatus status,
             finishProtocol(Fault);
             return 0;
     }
+    inputHook(input, size);
     inputBuffer.append(input, size);
     debug("StreamCore::readCallback(%s) inputBuffer=\"%s\", size %" Z "u\n",
         name(), inputBuffer.expand()(), inputBuffer.length());
diff --git a/src/StreamCore.h b/src/StreamCore.h
index e22c10f..9c8218d 100644
--- a/src/StreamCore.h
+++ b/src/StreamCore.h
@@ -219,6 +219,7 @@ class StreamCore :
 
 // virtual methods
     virtual void protocolStartHook() {}
+    virtual void inputHook(const void* input, size_t size) {};
     virtual void protocolFinishHook(ProtocolResult) {}
     virtual void startTimer(unsigned long timeout) = 0;
     virtual bool formatValue(const StreamFormat&, const void* fieldaddress) = 0;
diff --git a/src/StreamEpics.cc b/src/StreamEpics.cc
index bfc61a9..44b8d9e 100644
--- a/src/StreamEpics.cc
+++ b/src/StreamEpics.cc
@@ -137,6 +137,7 @@ class Stream : protected StreamCore
 #endif
 
 // StreamCore methods
+    void inputHook(const void* input, size_t size);
     void protocolFinishHook(ProtocolResult);
     void startTimer(unsigned long timeout);
     bool getFieldAddress(const char* fieldname,
@@ -934,6 +935,10 @@ process()
     debug("Stream::process(%s) start\n", name());
     status = NO_ALARM;
     convert = OK;
+    if (record->tpro)
+    {
+        StreamDebugClass(record->name).print("start protocol '%s'\n", protocolname());
+    }
     if (!startProtocol(record->proc == 2 ? StreamCore::StartInit : StreamCore::StartNormal))
     {
         debug("Stream::process(%s): could not start %sprotocol, status=%s (%d)\n",
@@ -1028,11 +1033,26 @@ expire(const epicsTime&)
 
 // StreamCore virtual methods ////////////////////////////////////////////
 
+void Stream::
+inputHook(const void* input, size_t size)
+{
+    if (record->tpro > 1)
+    {
+        StreamDebugClass(record->name).print("received \"%s\"\n",
+            StreamBuffer(input, size).expand()());
+    }
+}
+
 void Stream::
 protocolFinishHook(ProtocolResult result)
 {
     debug("Stream::protocolFinishHook(%s, %s)\n",
         name(), toStr(result));
+    if (record->tpro)
+    {
+        StreamDebugClass(record->name).print("%s. out=\"%s\", in=\"%s\"\n",
+            toStr(result), outputLine.expand()(), inputLine.expand()());
+    }
     switch (result)
     {
         case Success: