diff --git a/src/ProcessManager.cpp b/src/ProcessManager.cpp
index fe1e8df..7e94df1 100644
--- a/src/ProcessManager.cpp
+++ b/src/ProcessManager.cpp
@@ -29,7 +29,7 @@ void ProcessManager::run_writer(WriterManager& manager, const H5Format& format,
     boost::thread receiver_thread(receive_zmq, boost::ref(manager), boost::ref(ring_buffer), 
         boost::ref(receiver), boost::ref(format));
     boost::thread writer_thread(write_h5, boost::ref(manager), 
-        boost::ref(format), boost::ref(ring_buffer), boost::ref(*receiver.get_header_values_type()));
+        boost::ref(format), boost::ref(ring_buffer), receiver.get_header_values_type());
 
     RestApi::start_rest_api(manager, rest_port);
 
@@ -87,7 +87,7 @@ void ProcessManager::receive_zmq(WriterManager& manager, RingBuffer& ring_buffer
 }
 
 void ProcessManager::write_h5(WriterManager& manager, const H5Format& format, RingBuffer& ring_buffer,
-    const unordered_map<string, string>& header_values_type)
+    const shared_ptr<unordered_map<string, string>> header_values_type)
 {
     H5Writer writer(manager.get_output_file(), 0, config::initial_dataset_size, config::dataset_increase_step);
     auto raw_frames_dataset_name = config::raw_image_dataset_name;
@@ -133,27 +133,31 @@ void ProcessManager::write_h5(WriterManager& manager, const H5Format& format, Ri
 
         ring_buffer.release(received_data.first->buffer_slot_index);
 
-        // Write image metadata.
-        for (const auto& header_type : header_values_type) {
-            auto& name = header_type.first;
-            auto& type = header_type.second;
+        // Write image metadata if mapping specified.
+        if (header_values_type) {
 
-            auto value = received_data.first->header_values.at(name);
+            for (const auto& header_type : *header_values_type) {
 
-            // Header data are fixed to scalars in little endian.
-            vector<size_t> value_shape = {1};
-            auto endianness = "little";
-            auto value_bytes_size = type_to_size_mapping.at(type);
+                auto& name = header_type.first;
+                auto& type = header_type.second;
 
-            writer.write_data(name,
-                              received_data.first->frame_index,
-                              value.get(),
-                              value_shape,
-                              value_bytes_size,
-                              type,
-                              endianness);
+                auto value = received_data.first->header_values.at(name);
+
+                // Header data are fixed to scalars in little endian.
+                vector<size_t> value_shape = {1};
+                auto endianness = "little";
+                auto value_bytes_size = type_to_size_mapping.at(type);
+
+                writer.write_data(name,
+                                received_data.first->frame_index,
+                                value.get(),
+                                value_shape,
+                                value_bytes_size,
+                                type,
+                                endianness);
+            }
         }
-
+        
         manager.written_frame(received_data.first->frame_index);
     }
 
diff --git a/src/ProcessManager.hpp b/src/ProcessManager.hpp
index 9ae83d9..20f1f59 100644
--- a/src/ProcessManager.hpp
+++ b/src/ProcessManager.hpp
@@ -13,7 +13,7 @@ namespace ProcessManager
     void receive_zmq(WriterManager& manager, RingBuffer& ring_buffer, ZmqReceiver& receiver, const H5Format& format);
 
     void write_h5(WriterManager& manager, const H5Format& format, RingBuffer& ring_buffer,
-        const std::unordered_map<std::string, std::string>& header_values_type);
+        const std::shared_ptr<std::unordered_map<std::string, std::string>> header_values_type);
 };
 
 #endif
\ No newline at end of file
diff --git a/src/ZmqReceiver.cpp b/src/ZmqReceiver.cpp
index 4c902a0..8d2056a 100644
--- a/src/ZmqReceiver.cpp
+++ b/src/ZmqReceiver.cpp
@@ -8,8 +8,11 @@
 using namespace std;
 namespace pt = boost::property_tree;
 
-ZmqReceiver::ZmqReceiver(const std::string& connect_address, const int n_io_threads, const int receive_timeout) :
-    connect_address(connect_address), n_io_threads(n_io_threads), receive_timeout(receive_timeout), receiver(NULL)
+ZmqReceiver::ZmqReceiver(const std::string& connect_address, const int n_io_threads, const int receive_timeout,
+    shared_ptr<unordered_map<string, string>> header_values_type) :
+        connect_address(connect_address), n_io_threads(n_io_threads), 
+        receive_timeout(receive_timeout), receiver(NULL), header_values_type(header_values_type)
+
 {
     #ifdef DEBUG_OUTPUT
         cout << "[ZmqReceiver::ZmqReceiver] Creating ZMQ receiver with";
@@ -21,11 +24,6 @@ ZmqReceiver::ZmqReceiver(const std::string& connect_address, const int n_io_thre
 
     message_header = zmq::message_t(config::zmq_buffer_size_header);
     message_data = zmq::message_t(config::zmq_buffer_size_data);
-
-    header_values_type.reset(
-        new unordered_map<string, string>({
-            {"pulse_id", "uint64"},
-        }));
 }
 
 void ZmqReceiver::connect()
@@ -133,18 +131,20 @@ shared_ptr<FrameMetadata> ZmqReceiver::read_json_header(const string& header)
 
     header_data->type = json_header.get<string>("type");
 
-    for (const auto& value_mapping : *header_values_type) {
-        
-        const auto& name = value_mapping.first;
-        const auto& type = value_mapping.second;
+    if (header_values_type) {
+        for (const auto& value_mapping : *header_values_type) {
+            
+            const auto& name = value_mapping.first;
+            const auto& type = value_mapping.second;
 
-        auto value = get_value_from_json(json_header, name, type);
+            auto value = get_value_from_json(json_header, name, type);
 
-        header_data->header_values.insert(
-            {name, value}
-        );
+            header_data->header_values.insert(
+                {name, value}
+            );
+        }
     }
-
+    
     return header_data;
 }
 
diff --git a/src/ZmqReceiver.hpp b/src/ZmqReceiver.hpp
index 7f37a95..e3008fa 100644
--- a/src/ZmqReceiver.hpp
+++ b/src/ZmqReceiver.hpp
@@ -31,7 +31,8 @@ class ZmqReceiver
         const std::string& name, const std::string& type);
 
     public:
-        ZmqReceiver(const std::string& connect_address, const int n_io_threads, const int receive_timeout);
+        ZmqReceiver(const std::string& connect_address, const int n_io_threads, const int receive_timeout,
+            std::shared_ptr<std::unordered_map<std::string, std::string>> header_values_type=NULL);
 
         virtual ~ZmqReceiver(){};