diff --git a/src/dcc/Packet.cxx b/src/dcc/Packet.cxx
index 8d51abb29..757a448d5 100644
--- a/src/dcc/Packet.cxx
+++ b/src/dcc/Packet.cxx
@@ -346,6 +346,14 @@ void Packet::add_dcc_basic_accessory(unsigned address, bool is_activate)
     add_dcc_checksum();
 }
 
+void Packet::add_dcc_ext_accessory(unsigned address, uint8_t aspect)
+{
+    add_dcc_accy_address(false, address);
+    payload[dlc++] = aspect;
+    add_dcc_checksum();
+}
+
+
 void Packet::set_dcc_logon_enable(
     Defs::LogonEnableParam param, uint16_t cid, uint8_t session_id)
 {
diff --git a/src/dcc/Packet.cxxtest b/src/dcc/Packet.cxxtest
index 8cae24eb5..530c51968 100644
--- a/src/dcc/Packet.cxxtest
+++ b/src/dcc/Packet.cxxtest
@@ -373,6 +373,21 @@ TEST_F(PacketTest, DccBasicAccyPom)
             0b10011100));
 }
 
+TEST_F(PacketTest, DccExtAccySet)
+{
+    pkt_.add_dcc_ext_accessory(1733, 0x5a);
+    // 1733 = 0x6c5 = 0b 110 1100 0101
+    uint8_t b1 = 0b10110001;
+    uint8_t b2 = 0b00010011;
+    uint8_t b3 = 0x5a;
+    EXPECT_THAT(get_packet(), ElementsAre(b1, b2, b3, b1 ^ b2 ^ b3));
+
+    pkt_.clear();
+    pkt_.add_dcc_ext_accessory(1733, 0x80);
+    b3 = 0x80;
+    EXPECT_THAT(get_packet(), ElementsAre(b1, b2, b3, b1 ^ b2 ^ b3));
+}
+
 
 TEST_F(PacketTest, SvcProgDirectByte)
 {
diff --git a/src/dcc/Packet.hxx b/src/dcc/Packet.hxx
index c7ca853ad..712191d98 100644
--- a/src/dcc/Packet.hxx
+++ b/src/dcc/Packet.hxx
@@ -310,6 +310,17 @@ struct Packet : public DCCPacket
     /// @param is_normal true for normal, false for reverse
     /// @param is_activate true for activate, false for deactivate
     void set_dcc_basic_accy_params(bool is_normal, bool is_activate);
+
+    /// Adds a DCC extended accessory decoder command packet and the checksum
+    /// byte.
+    /// @param address is the 11-bit binary address, 0..2047. No bits have to be
+    /// inverted. This will be A10..A0 on the track. (To convert from a user
+    /// address, see accy_address_user_to_binary in dcc::Defs.)
+    /// @param aspect is the argument byte to the extended
+    /// accessory. Traditionally this was used as an aspect for a signal
+    /// decoder, but different accessories might have different interpretation
+    /// of it.
+    void add_dcc_ext_accessory(unsigned address, uint8_t aspect);
     
     /// Sets the packet to a logon enable packet.
     /// @param param defines which decoders should be requested to logon.
diff --git a/src/openlcb/DccAccyConsumer.cxxtest b/src/openlcb/DccAccyConsumer.cxxtest
index a09dbcb28..13bbac1f1 100644
--- a/src/openlcb/DccAccyConsumer.cxxtest
+++ b/src/openlcb/DccAccyConsumer.cxxtest
@@ -140,4 +140,66 @@ TEST_F(DccAccyTest, packet_throw)
     wait();
 }
 
+
+class DccExtAccyTest : public AsyncNodeTest
+{
+protected:
+    DccExtAccyTest()
+    {
+        wait();
+    }
+
+    StrictMock<MockPacketQueue> trackSendQueue_;
+    DccExtAccyConsumer consumer_{node_, &trackSendQueue_};
+};
+
+TEST_F(DccExtAccyTest, create)
+{
+}
+
+TEST_F(DccExtAccyTest, global_identify)
+{
+    clear_expect(true);
+    // Consumer range for one very long range  (11 bit plus 8 bit).
+    expect_packet(":X194A422AN010102000107FFFF;");
+    
+    // identify events addressed.
+    send_packet(":X19968111N022A;");
+    wait();
+}
+
+
+TEST_F(DccExtAccyTest, identify_unknown)
+{
+    // unknown identify
+    send_packet_and_expect_response(
+        ":X198F4111N0101020001035a77;", ":X194C722AN0101020001035a77;");
+}
+
+TEST_F(DccExtAccyTest, packet_throw)
+{
+    uint8_t hdr = 0b01100100;
+    EXPECT_CALL(trackSendQueue_,
+                arrived(hdr, ElementsAre(0b10110001, 0b00010011, 0xa5, _)));
+
+    // set to 0xa5
+    send_packet(":X195B4111N010102000106c5a5;");
+
+    
+    EXPECT_CALL(trackSendQueue_,
+                arrived(hdr, ElementsAre(0b10110001, 0b00010011, 0x00, _)));
+
+    // set to 0x00
+    send_packet(":X195B4111N010102000106c500;");
+
+    EXPECT_CALL(trackSendQueue_,
+                arrived(hdr, ElementsAre(0b10110001, 0b00010011, 0xff, _)));
+
+    // set to 0xff
+    send_packet(":X195B4111N010102000106c5ff;");
+    
+    wait();
+}
+
+
 } // namespace openlcb
diff --git a/src/openlcb/DccAccyConsumer.hxx b/src/openlcb/DccAccyConsumer.hxx
index 5bc716829..f486ea614 100644
--- a/src/openlcb/DccAccyConsumer.hxx
+++ b/src/openlcb/DccAccyConsumer.hxx
@@ -260,6 +260,150 @@ private:
     dcc::TrackIf *track_;
 };
 
+/// Base (generic protocol) implementation of the DCC extended accessory
+/// consumer. Unlike the basic accessory version, this one does not remember
+/// the last set state.
+class DccExtAccyConsumerBase : public SimpleEventHandler
+{
+protected:
+    /// How may addresses are there for extended accessories.
+    static constexpr unsigned NUM_ADDRESS = 2048;
+    /// How may aspects are supported per accessory.
+    static constexpr unsigned NUM_ASPECT = 256;
+    /// Total number of events we are listening for.
+    static constexpr unsigned NUM_EVENT = NUM_ASPECT * NUM_ADDRESS;
+    
+    /// Constructs a listener for DCC extended accessory control.
+    /// @param node is the virtual node that will be listening for events and
+    /// responding to Identify messages.
+    DccExtAccyConsumerBase(Node *node)
+        : node_(node)
+    {
+        EventRegistry::instance()->register_handler(
+            EventRegistryEntry(
+                this, TractionDefs::EXT_DCC_ACCESSORY_EVENT_BASE),
+            11+8 /*number of bits*/);
+    }
+
+    /// Destructor.
+    ~DccExtAccyConsumerBase()
+    {
+        EventRegistry::instance()->unregister_handler(this);
+    }
+
+    void handle_identify_global(const EventRegistryEntry &registry_entry,
+        EventReport *event, BarrierNotifiable *done) OVERRIDE
+    {
+        AutoNotify an(done);
+        if (event->dst_node && event->dst_node != node_)
+        {
+            return;
+        }
+        event->event_write_helper<1>()->WriteAsync(node_,
+            Defs::MTI_CONSUMER_IDENTIFIED_RANGE, WriteHelper::global(),
+            eventid_to_buffer(EncodeRange(
+                TractionDefs::EXT_DCC_ACCESSORY_EVENT_BASE, NUM_EVENT - 1)),
+            done->new_child());
+    }
+
+    void handle_event_report(const EventRegistryEntry &registry_entry,
+        EventReport *event, BarrierNotifiable *done) override
+    {
+        AutoNotify an(done);
+        if (!parse_event(event->event))
+        {
+            return;
+        }
+        send_accy_command();
+    }
+
+    void handle_identify_consumer(const EventRegistryEntry &entry,
+        EventReport *event, BarrierNotifiable *done) override
+    {
+        AutoNotify an(done);
+        if (!parse_event(event->event))
+        {
+            return;
+        }
+        event->event_write_helper<1>()->WriteAsync(node_,
+            Defs::MTI_CONSUMER_IDENTIFIED_UNKNOWN, WriteHelper::global(),
+            eventid_to_buffer(event->event), done->new_child());
+    }
+
+    /// Send the actual accessory command.
+    virtual void send_accy_command() = 0;
+
+    /// Parses an event into an openlcb accessory offset.
+    /// @return true if the event is in the accessory range, false if this
+    /// event can be ignored.
+    /// @param on_off will be set to true if this is an activate event, false
+    /// if it is an inactivate event.
+    /// @param ofs will be set to the offset in the state_ arrays.
+    /// @param mask will be set to a single bit value that marks the location
+    /// in the state_ arrays.
+    bool parse_event(EventId event)
+    {
+        if (event >= TractionDefs::EXT_DCC_ACCESSORY_EVENT_BASE &&
+            event <
+                TractionDefs::EXT_DCC_ACCESSORY_EVENT_BASE + NUM_EVENT)
+        {
+            aspect_ = event & 0xff;
+            dccAddress_ = (event >> 8) & (NUM_ADDRESS - 1);
+            return true;
+        }
+        else
+        {
+            return false;
+        }
+    }
+
+
+    /// Parsed event state: dcc address (0..2047) without inverting or encoding.
+    unsigned dccAddress_ : 11;
+    /// Parsed event state: the aspect commanded.
+    unsigned aspect_ : 8;
+
+    /// OpenLCB node to export the consumer on.
+    Node *node_;
+};
+
+/// Specialized (DCC protocol) implementation of a DCC extended accessory
+/// consumer.
+class DccExtAccyConsumer : public DccExtAccyConsumerBase
+{
+public:
+    /// Constructs a listener for DCC accessory control.
+    /// @param node is the virtual node that will be listening for events and
+    /// responding to Identify messages.
+    /// @param track is the interface through which we will be writing DCC
+    /// accessory packets.
+    DccExtAccyConsumer(Node *node, dcc::TrackIf *track)
+        : DccExtAccyConsumerBase(node)
+        , track_(track)
+    {
+    }
+
+    /// Destructor.
+    ~DccExtAccyConsumer()
+    {
+    }
+
+private:
+    /// Send the actual accessory command.
+    void send_accy_command() override
+    {
+        dcc::TrackIf::message_type *pkt;
+        mainBufferPool->alloc(&pkt);
+        pkt->data()->add_dcc_ext_accessory(dccAddress_, aspect_);
+        pkt->data()->packet_header.rept_count = 3;
+        track_->send(pkt);
+    }
+
+    /// Track to send DCC packets to.
+    dcc::TrackIf *track_;
+};
+
+
 } // namespace openlcb
 
 #endif  // _OPENLCB_DCCACCYCONSUMER_HXX_
diff --git a/src/openlcb/TractionDefs.hxx b/src/openlcb/TractionDefs.hxx
index 2ab6dbdb6..4927b0d4b 100644
--- a/src/openlcb/TractionDefs.hxx
+++ b/src/openlcb/TractionDefs.hxx
@@ -73,6 +73,8 @@ struct TractionDefs {
     static constexpr uint64_t ACTIVATE_BASIC_DCC_ACCESSORY_EVENT_BASE = 0x0101020000FF0000ULL;
     /// Base address of DCC accessory decoder well-known event range (inactive)
     static constexpr uint64_t INACTIVATE_BASIC_DCC_ACCESSORY_EVENT_BASE = 0x0101020000FE0000ULL;
+    /// Base address of DCC extended accessory decoder well-known event range
+    static constexpr uint64_t EXT_DCC_ACCESSORY_EVENT_BASE = 0x0101020001000000ULL;
     /// Node ID space allocated for DC blocks.
     static const uint64_t NODE_ID_DC_BLOCK = 0x060000000000ULL;
     /// Node ID space allocated for DCC locomotives.