diff -r f859d567f94e -r 42b62867574d master/fmmu_config.c
--- a/master/fmmu_config.c	Fri Jan 22 10:11:58 2016 +0100
+++ b/master/fmmu_config.c	Fri Jan 22 13:09:43 2016 +0100
@@ -60,13 +60,23 @@
     fmmu->sync_index = sync_index;
     fmmu->dir = dir;
 
-    fmmu->logical_start_address = domain->data_size;
-    fmmu->data_size = ec_pdo_list_total_size(
-            &sc->sync_configs[sync_index].pdos);
+    fmmu->logical_domain_offset = 0;
+    fmmu->data_size = 0;
 
     ec_domain_add_fmmu_config(domain, fmmu);
 }
 
+void ec_fmmu_set_domain_offset_size(
+        ec_fmmu_config_t *fmmu, /**< EtherCAT FMMU configuration. */
+        uint32_t logical_domain_offset, /**< Logical offset address
+            relative to domain->logical_base_address. */
+        unsigned data_size /**< Covered PDO size. */
+        )
+{
+    fmmu->logical_domain_offset = logical_domain_offset;
+    fmmu->data_size = data_size;
+}
+
 /*****************************************************************************/
 
 /** Initializes an FMMU configuration page.
@@ -79,13 +89,14 @@
         uint8_t *data /**> Configuration page memory. */
         )
 {
-    EC_CONFIG_DBG(fmmu->sc, 1, "FMMU: LogAddr 0x%08X, Size %3u,"
+    EC_CONFIG_DBG(fmmu->sc, 1, "FMMU: LogOff 0x%08X, Size %3u,"
             " PhysAddr 0x%04X, SM%u, Dir %s\n",
-            fmmu->logical_start_address, fmmu->data_size,
+            fmmu->logical_domain_offset, fmmu->data_size,
             sync->physical_start_address, fmmu->sync_index,
             fmmu->dir == EC_DIR_INPUT ? "in" : "out");
 
-    EC_WRITE_U32(data,      fmmu->logical_start_address);
+    EC_WRITE_U32(data,      fmmu->domain->logical_base_address +
+        fmmu->logical_domain_offset);
     EC_WRITE_U16(data + 4,  fmmu->data_size); // size of fmmu
     EC_WRITE_U8 (data + 6,  0x00); // logical start bit
     EC_WRITE_U8 (data + 7,  0x07); // logical end bit