diff --git a/src/ioc/db/chfPlugin.c b/src/ioc/db/chfPlugin.c
index 3548b6d6e..f249d854b 100644
--- a/src/ioc/db/chfPlugin.c
+++ b/src/ioc/db/chfPlugin.c
@@ -481,23 +481,23 @@ static long channel_open(chFilter *filter)
 }
 
 static void channel_register_pre(chFilter *filter,
-                                 chPostEventFunc **cb_out, void **arg_out)
+                                 chPostEventFunc **cb_out, void **arg_out, db_field_log *probe)
 {
     chfPlugin *p = (chfPlugin*) filter->plug->puser;
     chfFilter *f = (chfFilter*) filter->puser;
 
     if (p->pif->channelRegisterPre)
-        p->pif->channelRegisterPre(filter->chan, f->puser, cb_out, arg_out);
+        p->pif->channelRegisterPre(filter->chan, f->puser, cb_out, arg_out, probe);
 }
 
 static void channel_register_post(chFilter *filter,
-                                  chPostEventFunc **cb_out, void **arg_out)
+                                  chPostEventFunc **cb_out, void **arg_out, db_field_log *probe)
 {
     chfPlugin *p = (chfPlugin*) filter->plug->puser;
     chfFilter *f = (chfFilter*) filter->puser;
 
     if (p->pif->channelRegisterPost)
-        p->pif->channelRegisterPost(filter->chan, f->puser, cb_out, arg_out);
+        p->pif->channelRegisterPost(filter->chan, f->puser, cb_out, arg_out, probe);
 }
 
 static void channel_report(chFilter *filter, const char *intro, int level)
diff --git a/src/ioc/db/chfPlugin.h b/src/ioc/db/chfPlugin.h
index e95852d41..d6762481a 100644
--- a/src/ioc/db/chfPlugin.h
+++ b/src/ioc/db/chfPlugin.h
@@ -141,6 +141,10 @@ typedef struct chfPluginIf {
      * to be called when a data update is sent from the database towards the
      * event queue.
      *
+     * The plugin may find out the type of data it will receive by looking at 'probe'.
+     * If the plugin will change the data type and/or size, it must update 'probe'
+     * accordingly.
+     *
      * @param chan dbChannel for which the connection is being made.
      * @param pvt Pointer to private structure.
      * @param cb_out Pointer to this plugin's post-event callback (NULL to bypass
@@ -149,7 +153,8 @@ typedef struct chfPluginIf {
      *        this plugin's post-event callback.
      */
     void (* channelRegisterPre) (dbChannel *chan, void *pvt,
-                                 chPostEventFunc **cb_out, void **arg_out);
+                                 chPostEventFunc **cb_out, void **arg_out,
+                                 db_field_log *probe);
 
     /** @brief Register callbacks for post-event-queue operation.
      *
@@ -163,9 +168,9 @@ typedef struct chfPluginIf {
      * to be called when a data update is sent from the event queue towards the
      * final user.
      *
-     * The plugin must call the supplied 'st_in' function (from within
-     * its own set-type callback) with 'arg_in' as first argument after changing
-     * the data type and/or array size of 'chan'.
+     * The plugin may find out the type of data it will receive by looking at 'probe'.
+     * If the plugin will change the data type and/or size, it must update 'probe'
+     * accordingly.
      *
      * @param chan dbChannel for which the connection is being made.
      * @param pvt Pointer to private structure.
@@ -175,7 +180,8 @@ typedef struct chfPluginIf {
      *        this plugin's post-event callback.
      */
     void (* channelRegisterPost) (dbChannel *chan, void *pvt,
-                                  chPostEventFunc **cb_out, void **arg_out);
+                                  chPostEventFunc **cb_out, void **arg_out,
+                                  db_field_log *probe);
 
     /** @brief Channel report request.
      *
diff --git a/src/ioc/db/dbAccess.c b/src/ioc/db/dbAccess.c
index 5fabc7290..9a7cc4137 100644
--- a/src/ioc/db/dbAccess.c
+++ b/src/ioc/db/dbAccess.c
@@ -840,7 +840,7 @@ long epicsShareAPI dbGet(DBADDR *paddr, short dbrType,
             localAddr.field_type = pfl->field_type;
             localAddr.field_size = pfl->element_size;
             localAddr.no_elements = pfl->no_elements;
-            if (pfl->type == dbfl_type_value)
+            if (pfl->type == dbfl_type_val)
                 localAddr.pfield = (char *) &pfl->u.v.field;
             else
                 localAddr.pfield = (char *)  pfl->u.r.field;
@@ -876,7 +876,7 @@ long epicsShareAPI dbGet(DBADDR *paddr, short dbrType,
             localAddr.field_type = pfl->field_type;
             localAddr.field_size = pfl->element_size;
             localAddr.no_elements = pfl->no_elements;
-            if (pfl->type == dbfl_type_value)
+            if (pfl->type == dbfl_type_val)
                 localAddr.pfield = (char *) &pfl->u.v.field;
             else
                 localAddr.pfield = (char *)  pfl->u.r.field;
diff --git a/src/ioc/db/dbChannel.c b/src/ioc/db/dbChannel.c
index aaf150ba7..ca81540a9 100644
--- a/src/ioc/db/dbChannel.c
+++ b/src/ioc/db/dbChannel.c
@@ -44,7 +44,7 @@ static void chf_value(parseContext *parser, parse_result *presult)
 
     parser->filter = NULL;
     if (filter->plug->fif->parse_end(filter) == parse_continue) {
-        ellAdd(&parser->chan->filters, &filter->node);
+        ellAdd(&parser->chan->filters, &filter->list_node);
     } else {
         free(filter); // FIXME: Use free-list
         *presult = parse_stop;
@@ -445,57 +445,57 @@ long dbChannelOpen(dbChannel *chan)
     chPostEventFunc *func;
     void *arg;
     long status;
+    ELLNODE *node;
 
-    filter = (chFilter *) ellFirst(&chan->filters);
-    while (filter) {
-        /*
-         * Call channel_open for all filters
-         */
+    for (node = ellFirst(&chan->filters); node; node = ellNext(node)) {
+        filter = CONTAINER(node, chFilter, list_node);
+         /* Call channel_open */
         status = 0;
         if (filter->plug->fif->channel_open)
             status = filter->plug->fif->channel_open(filter);
         if (status) return status;
-
-        /*
-         * Build up the pre- and post-event-queue filter chains
-         */
-        func = NULL;
-        arg = NULL;
-        if (filter->plug->fif->channel_register_post) {
-            filter->plug->fif->channel_register_post(filter, &func, &arg);
-            if (func) {
-                ellAdd(&chan->post_chain, &filter->post_node);
-                filter->post_func = func;
-                filter->post_arg  = arg;
-            }
-        }
-        func = NULL;
-        arg = NULL;
-        if (filter->plug->fif->channel_register_pre) {
-            filter->plug->fif->channel_register_pre(filter, &func, &arg);
-            if (func) {
-                ellAdd(&chan->pre_chain, &filter->pre_node);
-                filter->pre_func = func;
-                filter->pre_arg  = arg;
-            }
-        }
-
-        filter = (chFilter *) ellNext(&filter->node);
     }
 
     /* Set up type probe */
     db_field_log probe;
-    db_field_log *pfl;
-    probe.type = dbfl_type_probe;
+    db_field_log p;
     probe.field_type  = dbChannelFieldType(chan);
     probe.no_elements = dbChannelElements(chan);
     probe.element_size  = dbChannelElementSize(chan);
+    p = probe;
 
-    /* Call filter chains to determine data type/size changes */
-    pfl = dbChannelRunPreChain(chan, &probe);
-    if (pfl != &probe) return -1;
-    pfl = dbChannelRunPostChain(chan, &probe);
-    if (pfl != &probe) return -1;
+    /*
+     * Build up the pre- and post-event-queue filter chains
+     * Separate loops because the probe must reach the filters in the right order.
+     */
+    for (node = ellFirst(&chan->filters); node; node = ellNext(node)) {
+        filter = CONTAINER(node, chFilter, list_node);
+        func = NULL;
+        arg = NULL;
+        if (filter->plug->fif->channel_register_pre) {
+            filter->plug->fif->channel_register_pre(filter, &func, &arg, &p);
+            if (func) {
+                ellAdd(&chan->pre_chain, &filter->pre_node);
+                filter->pre_func = func;
+                filter->pre_arg  = arg;
+                probe = p;
+            }
+        }
+    }
+    for (node = ellFirst(&chan->filters); node; node = ellNext(node)) {
+        filter = CONTAINER(node, chFilter, list_node);
+        func = NULL;
+        arg = NULL;
+        if (filter->plug->fif->channel_register_post) {
+            filter->plug->fif->channel_register_post(filter, &func, &arg, &p);
+            if (func) {
+                ellAdd(&chan->post_chain, &filter->post_node);
+                filter->post_func = func;
+                filter->post_arg  = arg;
+                probe = p;
+            }
+        }
+    }
 
     /* Save probe results */
     chan->final_no_elements  = probe.no_elements;
@@ -634,7 +634,7 @@ void dbChannelFilterShow(dbChannel *chan, const char *intro, int level)
     chFilter *filter = (chFilter *) ellFirst(&chan->filters);
     while (filter) {
         filter->plug->fif->channel_report(filter, intro, level);
-        filter = (chFilter *) ellNext(&filter->node);
+        filter = (chFilter *) ellNext(&filter->list_node);
     }
 }
 
diff --git a/src/ioc/db/dbChannel.h b/src/ioc/db/dbChannel.h
index e5c8c1040..04f571fd0 100644
--- a/src/ioc/db/dbChannel.h
+++ b/src/ioc/db/dbChannel.h
@@ -97,8 +97,8 @@ typedef struct chFilterIf {
 
     /* Channel operations: */
     long (* channel_open)(chFilter *filter);
-    void (* channel_register_pre) (chFilter *filter, chPostEventFunc **cb_out, void **arg_out);
-    void (* channel_register_post)(chFilter *filter, chPostEventFunc **cb_out, void **arg_out);
+    void (* channel_register_pre) (chFilter *filter, chPostEventFunc **cb_out, void **arg_out, db_field_log *probe);
+    void (* channel_register_post)(chFilter *filter, chPostEventFunc **cb_out, void **arg_out, db_field_log *probe);
     void (* channel_report)(chFilter *filter, const char *intro, int level);
     /* FIXME: More filter routines here ... */
     void (* channel_close)(chFilter *filter);
@@ -114,7 +114,7 @@ typedef struct chFilterPlugin {
 
 /* A chFilter holds data for a single filter instance */
 struct chFilter {
-    ELLNODE node;
+    ELLNODE list_node;
     ELLNODE pre_node;
     ELLNODE post_node;
     dbChannel *chan;
diff --git a/src/ioc/db/dbEvent.c b/src/ioc/db/dbEvent.c
index c652bdd5a..51ae1fec6 100644
--- a/src/ioc/db/dbEvent.c
+++ b/src/ioc/db/dbEvent.c
@@ -634,7 +634,7 @@ static db_field_log* db_create_event_log (struct evSubscrip *pevent)
         struct dbChannel *chan = pevent->chan;
         struct dbCommon  *prec = dbChannelRecord(chan);
         if (pevent->useValque) {
-            pLog->type = dbfl_type_value;
+            pLog->type = dbfl_type_val;
             pLog->stat = prec->stat;
             pLog->sevr = prec->sevr;
             pLog->time = prec->time;
diff --git a/src/ioc/db/db_field_log.h b/src/ioc/db/db_field_log.h
index fb5ebed5f..49cdb9d34 100644
--- a/src/ioc/db/db_field_log.h
+++ b/src/ioc/db/db_field_log.h
@@ -52,12 +52,11 @@ typedef void (dbfl_freeFunc)(struct db_field_log *pfl);
 /* Types of db_field_log: rec = use record, val = val inside, ref = reference inside */
 typedef enum dbfl_type {
     dbfl_type_rec = 0,
-    dbfl_type_value,
-    dbfl_type_ref,
-    dbfl_type_probe
+    dbfl_type_val,
+    dbfl_type_ref
 } dbfl_type;
 
-#define dbflTypeStr(t) (t==dbfl_type_value?"val":t==dbfl_type_rec?"rec":t==dbfl_type_probe?"prb":"ref")
+#define dbflTypeStr(t) (t==dbfl_type_val?"val":t==dbfl_type_rec?"rec":"ref")
 
 struct dbfl_val {
     union native_value field; /* Field value */
diff --git a/src/ioc/db/test/chfPluginTest.c b/src/ioc/db/test/chfPluginTest.c
index bba5f29ca..7c2613c44 100644
--- a/src/ioc/db/test/chfPluginTest.c
+++ b/src/ioc/db/test/chfPluginTest.c
@@ -166,13 +166,13 @@ static long channel_open(dbChannel *chan, void *user)
 }
 
 static void channelRegisterPre(dbChannel *chan, void *user,
-                               chPostEventFunc **cb_out, void **arg_out)
+                               chPostEventFunc **cb_out, void **arg_out, db_field_log *probe)
 {
     myStruct *my = (myStruct*)user;
 }
 
 static void channelRegisterPost(dbChannel *chan, void *user,
-                                chPostEventFunc **cb_out, void **arg_out)
+                                chPostEventFunc **cb_out, void **arg_out, db_field_log *probe)
 {
     myStruct *my = (myStruct*)user;
 }
diff --git a/src/ioc/db/test/dbChannelTest.c b/src/ioc/db/test/dbChannelTest.c
index ed69d6d84..df49c1183 100644
--- a/src/ioc/db/test/dbChannelTest.c
+++ b/src/ioc/db/test/dbChannelTest.c
@@ -116,11 +116,11 @@ long c_open(chFilter *filter)
     testOk(e & e_open, "channel_open called");
     return 0;
 }
-void c_reg_pre(chFilter *filter, chPostEventFunc **cb_out, void **arg_out)
+void c_reg_pre(chFilter *filter, chPostEventFunc **cb_out, void **arg_out, db_field_log *probe)
 {
     testOk(e & e_reg_pre, "channel_register_pre called");
 }
-void c_reg_post(chFilter *filter, chPostEventFunc **cb_out, void **arg_out)
+void c_reg_post(chFilter *filter, chPostEventFunc **cb_out, void **arg_out, db_field_log *probe)
 {
     testOk(e & e_reg_post, "channel_register_post called");
 }