diff --git a/csaxs/csaxs_h5_writer.cpp b/csaxs/csaxs_h5_writer.cpp
index 6a52b8d..7e6c677 100644
--- a/csaxs/csaxs_h5_writer.cpp
+++ b/csaxs/csaxs_h5_writer.cpp
@@ -11,15 +11,16 @@
 
 int main (int argc, char *argv[])
 {
-    if (argc != 6) {
+    if (argc != 7) {
         cout << endl;
         cout << "Usage: csaxs_h5_writer [connection_address] [output_file] [n_frames]";
-        cout << " [rest_port] [user_id]" << endl;
+        cout << " [rest_port] [user_id] [n_modules]" << endl;
         cout << "\tconnection_address: Address to connect to the stream (PULL). Example: tcp://127.0.0.1:40000" << endl;
         cout << "\toutput_file: Name of the output file." << endl;
         cout << "\tn_frames: Number of images to acquire. 0 for infinity (until /stop is called)." << endl;
         cout << "\trest_port: Port to start the REST Api on." << endl;
         cout << "\tuser_id: uid under which to run the writer. -1 to leave it as it is." << endl;
+        cout << "\tn_modules: Number of detector modules to be written." << endl;
         cout << endl;
 
         exit(-1);
@@ -30,6 +31,7 @@ int main (int argc, char *argv[])
     int n_frames =  atoi(argv[3]);
     int rest_port = atoi(argv[4]);
     int user_id = atoi(argv[5]);
+    int n_modules = atoi(argv[6]);
     string bsread_rest_address = "http://localhost:9999/";
 
     if (user_id != -1) {
@@ -38,9 +40,26 @@ int main (int argc, char *argv[])
 
     writer_utils::create_destination_folder(output_file);   
 
-    auto header_values = shared_ptr<unordered_map<string, HeaderDataType>>();
+    auto header_values = shared_ptr<unordered_map<string, HeaderDataType>>(new unordered_map<string, HeaderDataType> {
+        {"pulse_id", HeaderDataType("uint64")},
+        {"frame", HeaderDataType("uint64")},
+        {"is_good_frame", HeaderDataType("uint64")},
+        {"daq_rec", HeaderDataType("int64")},
 
-    CsaxsFormat format("data");
+        {"pulse_id_diff", HeaderDataType("int64", n_modules)},
+        {"framenum_diff", HeaderDataType("int64", n_modules)},
+
+        {"missing_packets_1", HeaderDataType("uint64", n_modules)},
+        {"missing_packets_2", HeaderDataType("uint64", n_modules)},
+        {"daq_recs", HeaderDataType("uint64", n_modules)},
+        
+        {"pulse_ids", HeaderDataType("uint64", n_modules)},
+        {"framenums", HeaderDataType("uint64", n_modules)},
+        
+        {"module_number", HeaderDataType("uint64", n_modules)}
+    });
+
+    CsaxsFormat format("images");
 
     WriterManager writer_manager(format.get_input_value_type(), output_file, n_frames);
     ZmqReceiver receiver(connect_address, config::zmq_n_io_threads, config::zmq_receive_timeout, header_values);