diff --git a/client.cc b/client.cc
index 6a3d0ff..57bd003 100644
--- a/client.cc
+++ b/client.cc
@@ -27,7 +27,7 @@ int num_requests = 0;								// request counter
 
 NetworkThread netthread;
 
-std::string to_hex8 (char v) {
+std::string to_hex8 (uint8_t v) {
 	char HEX[] = "0123456789ABCDEF";
 	int i = v;
 	int n;
@@ -41,7 +41,7 @@ std::string to_hex8 (char v) {
 	return txt;
 }
 
-std::string to_hex16 (int v) {
+std::string to_hex16 (uint16_t v) {
 	char HEX[] = "0123456789ABCDEF";
 	int i = v;
 	int n;
@@ -123,7 +123,13 @@ gboolean mbcli_thread_cb_net(gpointer data) {
 	char tmp[255];
 
 	printf ("%s:%d %s got some data\n", __FILE__, __LINE__, __FUNCTION__);
-	gtk_text_buffer_get_start_iter(textbuffer, &start);
+
+    if (data == NULL) {
+        fprintf (stderr, "%s:%d data not set\n", __FILE__, __LINE__);
+        return FALSE;
+    }
+
+    gtk_text_buffer_get_start_iter(textbuffer, &start);
 	gtk_text_buffer_get_end_iter(textbuffer, &end);
 	gtk_text_buffer_delete(textbuffer, &start, &end);
 
diff --git a/client.h b/client.h
index c1a2255..d622b36 100644
--- a/client.h
+++ b/client.h
@@ -53,8 +53,8 @@ void mbcli_set_update (int active);
 int mbcli_get_FC1516 ();
 void mbcli_readdata();
 gboolean mbcli_refreshtimeout(gpointer data);
-std::string to_hex16 (int v);
-std::string to_hex8 (char v);
+std::string to_hex16 (uint16_t v);
+std::string to_hex8 (uint8_t v);
 
 G_MODULE_EXPORT void mbcli_cb_show(GtkWidget *widget, gpointer data);
 G_MODULE_EXPORT void mbcli_cb_updateread (GtkToggleButton *togglebutton, gpointer user_data);
diff --git a/log.cc b/log.cc
index e4566bc..bb16e2c 100644
--- a/log.cc
+++ b/log.cc
@@ -21,6 +21,11 @@ void log_addtext (int logtype, std::string text, NWTReqResult *data) {
 	struct tm * curtime = localtime (&_tm);
 	static int _once = 0;
 
+    if (textview == NULL || textbuffer == NULL) {
+        fprintf (stderr, "%s:%d textview (%p) or textbuffer (%p) empty.\n", __FILE__, __LINE__, textview, textbuffer);
+        exit (1);
+    }
+
 	if (_once == 0) {
 		_once = 1;
 		tag_datetime = gtk_text_buffer_create_tag (textbuffer, "LogDateTime",
@@ -40,12 +45,14 @@ void log_addtext (int logtype, std::string text, NWTReqResult *data) {
     // display data if there are any
     //
     if (data != NULL && data->rawdatalen > 0 && data->rawdata != NULL) {
-        str = "";
+		printf ("%s rawdatalen:%d rawdata:%p\n", __FUNCTION__, data->rawdatalen, data->rawdata);
+		str = "";
         for (int i = 0; i < data->rawdatalen; i++) {
-            if (i & 16) str += "\n   ";
-            else if (i & 4 && i > 0) str += " ";
+            if ((i % 16) == 0) str += "\n   ";
+            else if ((i % 4) == 0 && i > 0) str += " ";
             str += to_hex8(data->rawdata[i]);
         }
+        printf ("\n%s:%d \n'%s'\n", __FILE__, __LINE__, str.c_str());
         gtk_text_buffer_insert_with_tags_by_name(textbuffer, &start, str.c_str(), -1, "LogData", NULL);
     }
 
diff --git a/nwthread.cc b/nwthread.cc
index 7e3c628..75e66db 100644
--- a/nwthread.cc
+++ b/nwthread.cc
@@ -193,7 +193,6 @@ void NetworkThread::BuildAndSendReadReq(char *buffer, int size) {
 	char *pos;
 	NWTReqResult *res = (NWTReqResult*) malloc(sizeof (NWTReqResult));
 
-
 	// req_mbh.transid++;		// with modbus tcp/ip it should always be set to 0
 	req_mbh.transid = 0;
 	pos = modbustcp_pkt_headerrq(buffer, size, &req_mbh);