diff --git a/src/db/dbCAC.h b/src/db/dbCAC.h
index c4bc60b70..ffd6653cf 100644
--- a/src/db/dbCAC.h
+++ b/src/db/dbCAC.h
@@ -44,7 +44,7 @@ public:
 class dbPutNotifyBlocker : public dbBaseIO {
 public:
     dbPutNotifyBlocker ( dbChannelIO &chanIn );
-    void initiatePutNotify ( epicsMutex &mutex, cacNotify &notify, struct dbAddr &addr, 
+    void initiatePutNotify ( epicsMutex &mutex, cacWriteNotify &notify, struct dbAddr &addr, 
             unsigned type, unsigned long count, const void *pValue );
     void cancel ();
     void completion ();
@@ -58,7 +58,7 @@ private:
     putNotify pn;
     epicsEvent block;
     dbChannelIO &chan;
-    cacNotify *pNotify;
+    cacWriteNotify *pNotify;
     dbSubscriptionIO * isSubscription ();
     static tsFreeList < dbPutNotifyBlocker > freeList;
     static epicsMutex freeListMutex;
@@ -70,7 +70,7 @@ extern "C" void dbSubscriptionEventCallback ( void *pPrivate, struct dbAddr *pad
 
 class dbSubscriptionIO : public tsDLNode <dbSubscriptionIO>, public dbBaseIO {
 public:
-    dbSubscriptionIO ( dbServiceIO &, dbChannelIO &, struct dbAddr &, cacDataNotify &, 
+    dbSubscriptionIO ( dbServiceIO &, dbChannelIO &, struct dbAddr &, cacStateNotify &, 
         unsigned type, unsigned long count, unsigned mask, cacChannel::ioid * );
     void destroy ();
     void show ( unsigned level ) const;
@@ -80,7 +80,7 @@ public:
 protected:
     virtual ~dbSubscriptionIO ();
 private:
-    cacDataNotify &notify;
+    cacStateNotify &notify;
     dbChannelIO &chan;
     dbEventSubscription es;
     unsigned type;
@@ -108,7 +108,9 @@ public:
         const dbAddr &addr, dbServiceIO &serviceIO );
     void destroy ();
     void callReadNotify ( unsigned type, unsigned long count, 
-            const struct db_field_log *pfl, cacDataNotify &notify );
+            cacReadNotify &notify );
+    void callStateNotify ( unsigned type, unsigned long count, 
+            const struct db_field_log *pfl, cacStateNotify &notify );
     void putNotifyCompletion ( dbPutNotifyBlocker & ); 
     void show ( unsigned level ) const;
     void * operator new ( size_t size);
@@ -121,13 +123,13 @@ private:
     const char *pName () const;
     void initiateConnect ();
     ioStatus read ( unsigned type, unsigned long count, 
-        cacDataNotify &, ioid * );
+        cacReadNotify &, ioid * );
     void write ( unsigned type, unsigned long count, 
         const void *pvalue );
     ioStatus write ( unsigned type, unsigned long count, 
-        const void *pvalue, cacNotify &, ioid * );
+        const void *pvalue, cacWriteNotify &, ioid * );
     void subscribe ( unsigned type, unsigned long count, 
-        unsigned mask, cacDataNotify &notify, ioid * );
+        unsigned mask, cacStateNotify &notify, ioid * );
     void ioCancel ( const ioid & );
     void ioShow ( const ioid &, unsigned level ) const;
     short nativeType () const;
@@ -143,11 +145,13 @@ public:
     virtual ~dbServiceIO ();
     cacChannel *createChannel ( const char *pName, cacChannelNotify & );
     void callReadNotify ( struct dbAddr &addr, unsigned type, unsigned long count, 
-            const struct db_field_log *pfl, cacDataNotify &notify );
+            cacReadNotify &notify );
+    void callStateNotify ( struct dbAddr &addr, unsigned type, unsigned long count, 
+            const struct db_field_log *pfl, cacStateNotify &notify );
     dbEventSubscription subscribe ( struct dbAddr &addr, dbChannelIO &chan,
         dbSubscriptionIO &subscr, unsigned mask, cacChannel::ioid * );
     void initiatePutNotify ( dbChannelIO &, struct dbAddr &, unsigned type, 
-        unsigned long count, const void *pValue, cacNotify &notify, 
+        unsigned long count, const void *pValue, cacWriteNotify &notify, 
         cacChannel::ioid *pId ); 
     void putNotifyCompletion ( dbPutNotifyBlocker & ); 
     void show ( unsigned level ) const;
diff --git a/src/db/dbChannelIO.cpp b/src/db/dbChannelIO.cpp
index 4e047f3e4..c63aeee9f 100644
--- a/src/db/dbChannelIO.cpp
+++ b/src/db/dbChannelIO.cpp
@@ -43,7 +43,7 @@ dbChannelIO::dbChannelIO ( cacChannelNotify &notify,
 
 void dbChannelIO::initiateConnect ()
 {
-    this->notify ().connectNotify ( *this );
+    this->notify ().connectNotify ();
 }
 
 dbChannelIO::~dbChannelIO ()
@@ -52,10 +52,10 @@ dbChannelIO::~dbChannelIO ()
 }
 
 cacChannel::ioStatus dbChannelIO::read ( unsigned type, 
-     unsigned long count, cacDataNotify &notify, ioid * ) 
+     unsigned long count, cacReadNotify &notify, ioid * ) 
 {
     this->serviceIO.callReadNotify ( this->addr, 
-        type, count, 0, notify );
+        type, count, notify );
     return iosSynch;
 }
 
@@ -72,7 +72,7 @@ void dbChannelIO::write ( unsigned type, unsigned long count, const void *pValue
 }
 
 cacChannel::ioStatus dbChannelIO::write ( unsigned type, unsigned long count, 
-                        const void *pValue, cacNotify &notify, ioid *pId ) 
+                        const void *pValue, cacWriteNotify &notify, ioid *pId ) 
 {
     if ( count > LONG_MAX ) {
         throw outOfBounds();
@@ -89,7 +89,7 @@ void dbChannelIO::putNotifyCompletion ( dbPutNotifyBlocker &blocker )
 }
 
 void dbChannelIO::subscribe ( unsigned type, unsigned long count, 
-    unsigned mask, cacDataNotify &notify, ioid *pId ) 
+    unsigned mask, cacStateNotify &notify, ioid *pId ) 
 {   
     if ( type > INT_MAX ) {
         throw cacChannel::badType();
diff --git a/src/db/dbChannelIOIL.h b/src/db/dbChannelIOIL.h
index 6ce4cdec5..713224c41 100644
--- a/src/db/dbChannelIOIL.h
+++ b/src/db/dbChannelIOIL.h
@@ -55,7 +55,14 @@ inline short dbChannelIO::nativeType () const
 }
 
 inline void dbChannelIO::callReadNotify ( unsigned type, unsigned long count, 
-        const struct db_field_log *pfl, cacDataNotify &notify )
+        cacReadNotify &notify )
 {
-    this->serviceIO.callReadNotify ( this->addr, type, count, pfl, notify );
+    this->serviceIO.callReadNotify ( this->addr, type, count, notify );
 }
+
+inline void dbChannelIO::callStateNotify ( unsigned type, unsigned long count, 
+        const struct db_field_log *pfl, cacStateNotify &notify )
+{
+    this->serviceIO.callStateNotify ( this->addr, type, count, pfl, notify );
+}
+
diff --git a/src/db/dbPutNotifyBlocker.cpp b/src/db/dbPutNotifyBlocker.cpp
index db40e4b9a..0da80994a 100644
--- a/src/db/dbPutNotifyBlocker.cpp
+++ b/src/db/dbPutNotifyBlocker.cpp
@@ -99,7 +99,7 @@ void dbPutNotifyBlocker::completion ()
     this->block.signal ();
 }
 
-void dbPutNotifyBlocker::initiatePutNotify ( epicsMutex &mutex, cacNotify &notify, 
+void dbPutNotifyBlocker::initiatePutNotify ( epicsMutex &mutex, cacWriteNotify &notify, 
         struct dbAddr &addr, unsigned type, unsigned long count, 
         const void *pValue )
 {
diff --git a/src/db/dbServiceIO.cpp b/src/db/dbServiceIO.cpp
index a8074563a..03783dd31 100644
--- a/src/db/dbServiceIO.cpp
+++ b/src/db/dbServiceIO.cpp
@@ -82,9 +82,57 @@ cacChannel *dbServiceIO::createChannel (
 }
 
 void dbServiceIO::callReadNotify ( struct dbAddr &addr, 
+        unsigned type, unsigned long count, 
+        cacReadNotify &notify )
+{
+    unsigned long size = dbr_size_n ( type, count );
+
+    if ( type > INT_MAX ) {
+        notify.exception ( ECA_BADTYPE, 
+            "type code out of range (high side)", 
+            type, count );
+        return;
+    }
+
+    if ( count > INT_MAX ) {
+        notify.exception ( ECA_BADCOUNT, 
+            "element count out of range (high side)",
+            type, count);
+        return;
+    }
+
+    epicsAutoMutex locker ( this->mutex );
+
+    if ( this->eventCallbackCacheSize < size) {
+        if ( this->pEventCallbackCache ) {
+            delete [] this->pEventCallbackCache;
+        }
+        this->pEventCallbackCache = new char [size];
+        if ( ! this->pEventCallbackCache ) {
+            this->eventCallbackCacheSize = 0ul;
+            notify.exception ( ECA_ALLOCMEM, 
+                "unable to allocate callback cache",
+                type, count );
+            return;
+        }
+        this->eventCallbackCacheSize = size;
+    }
+    int status = db_get_field ( &addr, static_cast <int> ( type ), 
+                    this->pEventCallbackCache, static_cast <int> ( count ), 0 );
+    if ( status ) {
+        notify.exception ( ECA_GETFAIL, 
+            "db_get_field() completed unsuccessfuly",
+            type, count);
+    }
+    else { 
+        notify.completion ( type, count, this->pEventCallbackCache );
+    }
+}
+
+void dbServiceIO::callStateNotify ( struct dbAddr &addr, 
         unsigned type, unsigned long count, 
         const struct db_field_log *pfl, 
-        cacDataNotify &notify )
+        cacStateNotify &notify )
 {
     unsigned long size = dbr_size_n ( type, count );
 
@@ -127,7 +175,7 @@ void dbServiceIO::callReadNotify ( struct dbAddr &addr,
             type, count);
     }
     else { 
-        notify.completion ( type, count, this->pEventCallbackCache );
+        notify.current ( type, count, this->pEventCallbackCache );
     }
 }
 
@@ -198,7 +246,7 @@ dbEventSubscription dbServiceIO::subscribe ( struct dbAddr &addr, dbChannelIO &c
 
 void dbServiceIO::initiatePutNotify ( dbChannelIO &chan, struct dbAddr &addr, 
     unsigned type, unsigned long count, const void *pValue, 
-    cacNotify &notify, cacChannel::ioid *pId )
+    cacWriteNotify &notify, cacChannel::ioid *pId )
 {
     epicsAutoMutex locker ( this->mutex );
     if ( ! chan.dbServicePrivateListOfIO::pBlocker ) {
diff --git a/src/db/dbSubscriptionIO.cpp b/src/db/dbSubscriptionIO.cpp
index dddc0793e..64aece360 100644
--- a/src/db/dbSubscriptionIO.cpp
+++ b/src/db/dbSubscriptionIO.cpp
@@ -33,7 +33,7 @@ tsFreeList < dbSubscriptionIO > dbSubscriptionIO::freeList;
 epicsMutex dbSubscriptionIO::freeListMutex;
 
 dbSubscriptionIO::dbSubscriptionIO ( dbServiceIO &serviceIO, dbChannelIO &chanIO, 
-    dbAddr &addr, cacDataNotify &notifyIn, 
+    dbAddr &addr, cacStateNotify &notifyIn, 
     unsigned typeIn, unsigned long countIn, unsigned maskIn,
     cacChannel::ioid * pId ) :
     notify ( notifyIn ), chan ( chanIO ), es ( 0 ), 
@@ -73,7 +73,7 @@ extern "C" void dbSubscriptionEventCallback ( void *pPrivate, struct dbAddr * /*
 	int /* eventsRemaining */, struct db_field_log *pfl )
 {
     dbSubscriptionIO *pIO = static_cast < dbSubscriptionIO * > ( pPrivate );
-    pIO->chan.callReadNotify ( pIO->type, pIO->count, pfl, pIO->notify );
+    pIO->chan.callStateNotify ( pIO->type, pIO->count, pfl, pIO->notify );
 }
 
 void dbSubscriptionIO::show ( unsigned level ) const