diff --git a/ascon.c b/ascon.c
index a017e1c8..a60b3fcd 100644
--- a/ascon.c
+++ b/ascon.c
@@ -75,9 +75,9 @@ static void AsconError(Ascon *a, char *msg, int errorno) {
     state = stateText[a->state];
   }
   if (errorno != 0) {
-    ErrPutMsg(&a->errList, NULL, "%s %s (during %s)", msg, strerror(errorno), state);
+    ErrPutMsg(a->errList, "%s %s (during %s)", msg, strerror(errorno), state);
   } else {
-    ErrPutMsg(&a->errList, NULL, "%s (during %s)", msg, state);
+    ErrPutMsg(a->errList, "%s (during %s)", msg, state);
   }
   a->state |= AsconFailed;
 }
@@ -400,7 +400,7 @@ Ascon *AsconMake(SConnection *con, int argc, char *argv[]) {
   }
   a->rdBuffer = CreateDynString(60, 63);
   a->wrBuffer = CreateDynString(60, 63);
-  a->errList.head = NULL;
+  a->errList = NULL;
   a->responseValid = 0;
   a->timeout = 2.0;
   a->reconnectInterval = 10;
@@ -500,6 +500,6 @@ char *AsconRead(Ascon *a) {
   return NULL;
 }
 
-ErrMsgList *AsconGetErrList(Ascon *a) {
-  return &a->errList;
+ErrMsg *AsconGetErrList(Ascon *a) {
+  return a->errList;
 }
diff --git a/ascon.h b/ascon.h
index 75b417e8..fe6f4d32 100644
--- a/ascon.h
+++ b/ascon.h
@@ -64,7 +64,7 @@ char *AsconRead(Ascon *a);
 /** \brief get the connections error list
  *  \return the error list
  */
-ErrMsgList *AsconGetErrList(Ascon *a);
+ErrMsg *AsconGetErrList(Ascon *a);
 
 /** \brief a helper function
  *  \param argc the number of args
diff --git a/ascon.i b/ascon.i
index 0bffb423..0d0f6f38 100644
--- a/ascon.i
+++ b/ascon.i
@@ -64,7 +64,7 @@ struct Ascon {
   int wrPos;          /**< write buffer position */
   double timeout;     /**< read timeout (sec) */
   char *hostport;     /**< host:port to connect */
-  ErrMsgList errList; /**< error message list */
+  ErrMsg *errList;    /**< error message list */
   double start;       /**< unix time when read was started */
   void *private;      /**< private data of protocol */
   int noResponse;     /**< no response expected */
diff --git a/devser.c b/devser.c
index aa559ec1..569a398c 100644
--- a/devser.c
+++ b/devser.c
@@ -117,7 +117,8 @@ int DevQueueTask(void *ds) {
   while (action != NULL) {
     status = AsconTask(devser->asyncConn);
     if (status == AsconFailure) {
-      /* TODO: error handling */
+      devser->errmsg = AsconGetErrList(devser->asyncConn);
+      return 1;
     } else if (status != AsconReady) {
       return 1;
     }
diff --git a/errormsg.c b/errormsg.c
index 488f26d8..cd45eda1 100644
--- a/errormsg.c
+++ b/errormsg.c
@@ -4,13 +4,30 @@
 #include <string.h>
 #include "errormsg.h"
 
-/* ErrMsgList implementation */
-#define MC_NAME(T) ErrMsg##T
-#define MC_IMPLEMENTATION
-#include "mclist.c"
+/* compare two strings for euqality, ignoring text within square brackets */
+int ErrEqual(char *str1, char *str2) {
+  char *p;
+  
+  while (*str1 != '\0' || *str2 != '\0') {
+    if (*str1 != *str2) {
+      return 0;
+    }
+    if (*str1 == '[') {
+      str1 = strchr(str1, ']');
+      str2 = strchr(str2, ']');
+      if (str1 == NULL || str2 == NULL) {
+        return str1 == str2;
+      }
+      str1++;
+      str2++;
+    }
+  }
+  return 1;
+}
 
-ErrMsg *ErrPutMsg(ErrMsgList *dump, char *data, char *fmt, ...) {
-  ErrMsg *m, *p;
+ErrMsg *ErrPutMsg(ErrMsg *dump, char *fmt, ...) {
+  ErrMsg *m;
+  ErrMsg **last;
   va_list ap;
   char buf[256];
   char *text;
@@ -28,36 +45,23 @@ ErrMsg *ErrPutMsg(ErrMsgList *dump, char *data, char *fmt, ...) {
     vsnprintf(text, l, fmt, ap);
     va_end(ap);
   }
-  
-  m = NULL;
-  for (p = ErrMsgFirst(dump); p!= NULL; p = ErrMsgNext(dump)) {
-    if (strcmp(text, p->text) == 0) {
-      m = ErrMsgTake(dump);
+  for (last = &dump; *last != NULL; last = &m->next) {
+    m = *last;
+    if (ErrEqual(text, m->text)) {
+      *last = m->next;
       break;
     }
   }
   if (m == NULL) {
+    if (text == buf) text = strdup(buf);
     m = calloc(1, sizeof(*m));
-    if (text == buf) {
-      m->text = strdup(text);
-    } else {
-      m->text = text;
-    }
-    m->data = NULL;
+    m->text = text;
     m->cnt = 1;
   } else {
     if (text != buf) free(text);
     m->cnt++;
   }
-  if (m->data) {
-    free(m->data);
-    m->data = NULL;
-  }
-  if (data) {
-    m->data = strdup(data);
-  }
-  ErrMsgFirst(dump);
-  ErrMsgInsert(dump, m);
+  m->next = dump;
   time(&m->last);
   return m;
 }
diff --git a/errormsg.h b/errormsg.h
index 70efc753..9c20ec64 100644
--- a/errormsg.h
+++ b/errormsg.h
@@ -11,20 +11,22 @@
 typedef struct ErrMsg {
   struct ErrMsg *next;
   char *text;   /**< the message text */
-  char *data;   /**< additional text which may be different for the same message */
+  char *cmpr;   /**< compressed message text */
   int cnt;      /**< count */
   time_t last;  /**< time of last message */
 } ErrMsg;
 
-/* define type ErrMsgList and functions ErrMsgAdd etc. */
-#define MC_NAME(T) ErrMsg##T
-#include "mclist.h"
-
 /** \brief Put a formatted message to the error message list
+ *
+ * The error message list contains only one entry for all messages
+ * with the same text, storing only the count and the last used time.
+ * Characters within sqaure brackets are not taken into account
+ * when comparing messages.
+ *
  *  \param dump the error message list
- *  \param data some additional text (may be NULL)
  *  \param fmt the format for the message
+ *  \return the new error message list head
  */
-ErrMsg *ErrPutMsg(ErrMsgList *dump, char *data, char *fmt, ...);
+ErrMsg *ErrPutMsg(ErrMsg *dump, char *fmt, ...);
 
 #endif
diff --git a/hipadaba.c b/hipadaba.c
index 2b4585b7..4a359a95 100644
--- a/hipadaba.c
+++ b/hipadaba.c
@@ -914,7 +914,9 @@ static int calcDataLength(pHdb node, int testLength){
 /*============================= Property Functions ==========================*/
  void SetHdbProperty(pHdb node, char *key, char *value){
  	if(node != NULL && key != NULL && node->properties != NULL){
- 		if(StringDictExists(node->properties, key)){
+ 		if (value == NULL) {
+ 			StringDictDelete(node->properties, key);
+ 		} else if(StringDictExists(node->properties, key)){
 	 		StringDictUpdate(node->properties,key,value);
  		} else {
  			StringDictAddPair(node->properties,key,value);
diff --git a/scriptcontext.c b/scriptcontext.c
index 478eb529..186e373b 100644
--- a/scriptcontext.c
+++ b/scriptcontext.c
@@ -17,16 +17,19 @@
 
 #define MAX_HDB_PATH 1024
 
+typedef struct ContextItem {
+  struct ContextItem *next;
+  Hdb *node;
+  Hdb *controllerNode;
+} ContextItem;
+
 typedef struct ScriptContext {
   ObjectDescriptor *desc;
-  Hdb *node;
+  ContextItem *nodes;
+  ContextItem *trash;
+  ContextItem *base;
 } ScriptContext;
 
-typedef struct ContextStack {
-  struct ContextStack *next;
-  Hdb *node;
-} ContextStack;
-
 typedef struct SctController {
   DevSer *devser;
   Hdb *node; /* the controller node */
@@ -43,9 +46,7 @@ typedef struct SctData {
   Hdb *node; /* back link used by SctMatchWrite/SctMatchPoll */
 } SctData;
 
-static ScriptContext *nctx = NULL; /* the node context */
-static ScriptContext *cctx = NULL; /* the controller context */
-static ContextStack *stack, *stackTrash;
+static ScriptContext *sct = NULL;
 static SCStore *currentCon = NULL;
 
 static struct {
@@ -54,31 +55,60 @@ static struct {
 
 static char *mainCallback = "main callback";
 
-void PushContext(Hdb *node) {
-  ContextStack *new;
+void PushContext(Hdb *node, Hdb *controllerNode) {
+  ContextItem *new;
   
-  if (stackTrash == NULL) {
+  if (sct->trash == NULL) {
     new = calloc(1, sizeof(*new));
   } else {
-    new = stackTrash;
-    stackTrash = stackTrash->next;
+    new = sct->trash;
+    sct->trash = sct->trash->next;
   }
-  new->next = stack;
+  new->next = sct->nodes;
+  sct->nodes = new;
   new->node = node;
-  stack = new;
+  new->controllerNode = controllerNode;
 }
 
-Hdb *PopContext(void) {
-  ContextStack *c;
+void PopContext(void) {
+  ContextItem *c;
   
-  c = stack;
-  stack = stack->next;
-  c->next = stackTrash;
-  stackTrash = c;
-  return c->node;
+  c = sct->nodes;
+  assert(c);
+  sct->nodes = c->next;
+  c->next = sct->trash;
+  sct->trash = c;
 }
 
-static void SetProp(Hdb *node, char *key, char *value) {
+void CleanStack(Hdb *node) {
+  ContextItem *s;
+  
+  /* clean context from killed nodes */
+  for (s = sct->nodes; s != NULL; s = s->next) {
+    if (s->node == node) {
+      s->node = NULL;
+    }
+    if (s->controllerNode == node) {
+      s->controllerNode = NULL;
+    }
+  }
+}
+
+static void SetProp(Hdb *node, Hdb *cNode, char *key, char *value) {
+  char *val;
+  
+  if (node == NULL) {
+    if (cNode == NULL) return;
+    node = cNode;
+  } else {
+    val = GetHdbProp(node, key);
+    if (val == NULL && cNode != NULL) {
+      val = GetHdbProp(cNode, key);
+      if (val != NULL) {
+        node = cNode;
+      }
+    }
+  }
   if (value == NULL) {
     if (GetHdbProperty(node, key, NULL, 0) > 0) {
       SetHdbProperty(node, key, "");
@@ -88,14 +118,28 @@ static void SetProp(Hdb *node, char *key, char *value) {
   }
 }
 
+static char *GetProp(Hdb *node, Hdb *cNode, char *key) {
+  char *val;
+
+  if (node != NULL) {
+    val = GetHdbProp(node, key);
+    if (val != NULL) return val;
+  }
+  if (cNode != NULL) {
+    val = GetHdbProp(node, key);
+  }
+  return val;
+}
+
 int SctCommand(SConnection *con, SicsInterp *sics, void *object,
                int argc, char *argv[]) {
-  ScriptContext *ctx = object;
   static char value[1024];
   char *val;
-  Hdb *node = ctx->node;
+  Hdb *node = sct->nodes->node;
+  Hdb *cNode = sct->nodes->controllerNode;
   
-  if (node == NULL) {
+  assert(sct == object);
+  if (node == NULL && cNode == NULL) {
     SCPrintf(con, eError, "ERROR: %s may be called only in proper context",
       argv[0]);
     return 0;
@@ -106,7 +150,7 @@ int SctCommand(SConnection *con, SicsInterp *sics, void *object,
     return 1;
   }
   if (argc == 2) { /* get case */
-    val = GetHdbProp(node, argv[1]);
+    val = GetProp(node, cNode, argv[1]);
     if (val == NULL) {
       SCPrintf(con, eError, "ERROR: %s %s not found", argv[0], argv[1]);
       return 0;
@@ -114,10 +158,8 @@ int SctCommand(SConnection *con, SicsInterp *sics, void *object,
     SCWrite(con, val, eValue);
   } else { /* set case */
     val = Arg2Tcl(argc-2, argv+2, value, sizeof value);
-    if (val != NULL) {
-      SetHdbProperty(node, argv[1], val);
-      if (val != value) free(val);
-    }
+    SetProp(node, cNode, argv[1], val);
+    if (val != NULL && val != value) free(val);
   }
   return 1;
 }
@@ -130,10 +172,7 @@ int SctCallInContext(SConnection *con, char *script, Hdb *node,
   int iRet = 1;
   int verbose = controller->verbose;
   
-  PushContext(nctx->node);
-  PushContext(cctx->node);
-  nctx->node = node;
-  cctx->node = controller->node;
+  PushContext(node, controller->node);
   if (verbose) {
     SCPrintf(con, eInError, "\nscript: %s\n", script);
   }
@@ -149,32 +188,11 @@ int SctCallInContext(SConnection *con, char *script, Hdb *node,
   }
   *resPtr = result;
 
-  cctx->node = PopContext();
-  nctx->node = PopContext();
+  PopContext();
+  PopContext();
   return iRet;
 }
 
-void SctKill(void *object) {
- ScriptContext *ctx = object;
-  if (ctx == nctx) nctx = NULL;
-  if (ctx == cctx) cctx = NULL;
-  if (ctx->desc != NULL) {
-    DeleteDescriptor(ctx->desc);
-  }
-  free(object);
-}
-
-ScriptContext *SctMake(char *name) {
-  ScriptContext *ctx;
-  
-  ctx = calloc(1, sizeof(*ctx));
-  assert(ctx);
-  ctx->desc = CreateDescriptor("ScriptContext");
-  ctx->node = NULL;
-  AddCommand(pServ->pSics, name, SctCommand, SctKill, ctx);
-  return ctx;
-}
-
 static int SctMatch(void *data1, void *data2) {
   SctData *a = data1;
   SctData *b = data2;
@@ -198,18 +216,18 @@ static char *SctActionHandler(void *actionData, char *lastReply) {
   } else {
     con = SCStorePush(controller->conn);
   }
-  SetProp(controller->node, "result", lastReply);
+  SetProp(node, controller->node, "result", lastReply);
   if (controller->verbose && lastReply != NULL && *lastReply != '\0') {
     SCPrintf(con, eWarning, "reply : %s", lastReply);
   }
-  state = GetHdbProp(controller->node, "state");
-  if (state == NULL || state[0] == '\0') {
+  state = GetProp(node, controller->node, "state");
+  if (state == NULL || strcasecmp(state, "idle") == 0) {
     state = data->name;
-    SetProp(controller->node, "state", state);
+    SetProp(node, controller->node, "state", state);
   }
   for (i = 0; i < 10; i++) {
-    SetProp(controller->node, "send", NULL);
-    script = GetHdbProp(node, state);
+    SetProp(node, controller->node, "send", NULL);
+    script = GetProp(node, controller->node, state);
     if (script == NULL) script = state;
 
     if (! SctCallInContext(con, script, node, data->controller, &result)) {
@@ -227,8 +245,8 @@ static char *SctActionHandler(void *actionData, char *lastReply) {
       }
       goto finish;
     }
-    SetProp(controller->node, "state", state);
-    send = GetHdbProp(controller->node, "send");
+    SetProp(node, controller->node, "state", state);
+    send = GetProp(node, controller->node, "send");
     if (send != NULL && send[0] != '\0') {
       if (controller->verbose) {
         SCPrintf(con, eWarning, "send  : %s", send);
@@ -238,7 +256,7 @@ static char *SctActionHandler(void *actionData, char *lastReply) {
   }
   SCPrintf(con, eError, "ERROR: too many quick scripts chained");
 finish:
-  SetProp(controller->node, "state", "");
+  SetProp(node, controller->node, "state", "idle");
 quit:
   if (currentCon) {
     SCStorePop(currentCon);
@@ -267,7 +285,7 @@ static hdbCallbackReturn SctMainCallback(Hdb *node, void *userData,
   hdbDataMessage *mm;
   hdbPtrMessage *pm;
   hdbMessage *km;
-  ContextStack *s;
+  ContextItem *s;
   SConnection *con;
   char *geterror;
 
@@ -288,14 +306,7 @@ static hdbCallbackReturn SctMainCallback(Hdb *node, void *userData,
   }
   km = GetHdbKillNodeMessage(msg);
   if (km != NULL) {
-    /* clean context from killed nodes */
-    for (s = stack; s != NULL; s = s->next) {
-      if (s->node == node) {
-        s->node = NULL;
-      }
-    }
-    if (cctx->node == node) cctx->node = NULL;
-    if (nctx->node == node) nctx->node = NULL;
+    CleanStack(node);
     return hdbContinue;
   }
   mm = GetHdbGetMessage(msg);
@@ -353,7 +364,7 @@ static hdbCallbackReturn SctActionCallback(Hdb *node, void *userData,
     con = mm->callData;
     
     /* call check script, if available */
-    script = GetHdbProp(node, "check");
+    script = GetProp(node, data->controller->node, "check");
     if (script != NULL) {
       if (SctCallInContext(con, script, node, data->controller, &error) == 0) {
         SCPrintf(con, eError, "ERROR: %s", error);
@@ -366,7 +377,7 @@ static hdbCallbackReturn SctActionCallback(Hdb *node, void *userData,
     SetHdbProperty(node, "target", GetCharArray(text));
     
     /* enqueue write action */
-    writeprio = GetHdbProp(node, "writeprio");
+    writeprio = GetProp(node, data->controller->node, "writeprio");
     if (writeprio != NULL) {
       prio = DevText2Prio(writeprio);
       if (prio < 0) prio = WritePRIO;
@@ -492,9 +503,7 @@ static int SctPollCmd(pSICSOBJ ccmd, SConnection *con,
 
   SctAddPollNode(controller, node, interval, prio, action);
 
-  if (stack == NULL) {
-    nctx->node = node;
-  }
+  sct->base->node = node;
 
   return 1;
 }
@@ -555,9 +564,7 @@ static int SctWriteCmd(pSICSOBJ ccmd, SConnection *con,
     return 0;
   }
   
-  if (stack == NULL) {
-    nctx->node = node;
-  }
+  sct->base->node = node;
   return 1;
 }
 
@@ -642,6 +649,7 @@ static hdbCallbackReturn SctDebugCallback(Hdb *node, void *userData,
 static void SctKillController(void *c) {
   SctController *controller = c;
   
+  CleanStack(controller->node);
   RemoveSICSInternalCallback(controller);
   DevKill(controller->devser);
 }
@@ -680,8 +688,6 @@ static int SctMakeController(SConnection *con, SicsInterp *sics,
   AddCommand(pServ->pSics, nodeName, InvokeSICSOBJ, KillSICSOBJ, ccmd);
   SetDescriptorKey(ccmd->pDes, "creationCommand", "0");
 
-  SetProp(controller->node, "state", "");
-
   AddHipadabaChild(parent, controller->node, con);
 
   controller->devser = DevMake(con, argc - 2, argv + 2);
@@ -710,16 +716,38 @@ static int SctMakeController(SConnection *con, SicsInterp *sics,
   cb = MakeHipadabaCallback(SctDebugCallback, controller, NULL);
   if (cb) AppendHipadabaCallback(par, cb);
   
-  if (stack == NULL) {
-    cctx->node = controller->node;
-    nctx->node = NULL;
-  }
-  
+  sct->base->controllerNode = controller->node;
+  sct->base->node = NULL;
+
   return 1;
 }
 
+void SctKill(void *object) {
+  assert(sct == object);
+  ContextItem *p, *q;
+  
+  for (p = sct->nodes; p != NULL; p = q) {
+    q = p->next;
+    free(p);
+  }
+  for (p = sct->trash; p != NULL; p = q) {
+    q = p->next;
+    free(p);
+  }
+  if (sct->desc != NULL) {
+    DeleteDescriptor(sct->desc);
+  }
+  free(sct);
+  sct = NULL;
+}
+
 void SctInit(void) {
-  nctx = SctMake("nctx");
-  cctx = SctMake("cctx");
+  if (sct) return;
+  sct = calloc(1, sizeof(*sct));
+  assert(sct);
+  sct->desc = CreateDescriptor("ScriptContext");
+  PushContext(NULL, NULL);
+  sct->base = sct->nodes;
+  AddCommand(pServ->pSics, "sct", SctCommand, SctKill, sct);
   AddCmd("makesctcontroller", SctMakeController);
 }
diff --git a/sicshipadaba.c b/sicshipadaba.c
index e501ccf4..6483176e 100644
--- a/sicshipadaba.c
+++ b/sicshipadaba.c
@@ -2932,6 +2932,7 @@ static int SetSICSHdbProperty(SConnection *pCon, SicsInterp *pSics, void *pData,
     int argc, char *argv[]){
     pHdb targetNode = NULL;
     char buffer[512];
+    char *val;
 
     if(argc < 4) {
         SCWrite(pCon,"ERROR: need path key value as parameters",eError);
@@ -2942,8 +2943,11 @@ static int SetSICSHdbProperty(SConnection *pCon, SicsInterp *pSics, void *pData,
     	SCWrite(pCon,"ERROR: node not found",eError);
         return 0;
     }
-    Arg2Tcl(argc-3, &argv[3], buffer,512);
-    SetHdbProperty(targetNode,argv[2], buffer);
+    val = Arg2Tcl(argc-3, &argv[3], buffer, sizeof buffer);
+    if (val) {
+      SetHdbProperty(targetNode,argv[2], val);
+      if (val != buffer) free(val);
+    }
     SCSendOK(pCon);
     return 1;
  }