diff --git a/detect.h b/detect.h
index 68806b6..4ca028c 100644
--- a/detect.h
+++ b/detect.h
@@ -65,6 +65,8 @@ class PosCtl {
 
 		int OutputClose();
 		int OutputOpen();
+		int WriteTTY(char *);
+		int ReadTTY(char *, int);
 	public:
 		PosCtl();
 		~PosCtl() {};
diff --git a/posctl.cc b/posctl.cc
index b6f9902..90e7ba2 100644
--- a/posctl.cc
+++ b/posctl.cc
@@ -664,10 +664,58 @@ int PosCtl::OutputOpen() {
 	return 0;
 };
 
+int PosCtl::WriteTTY (char * outbuf) {
+	ssize_t len;
+	
+	printf ("%s:%d %s send: '%s'\n", __FILE__, __LINE__, __FUNCTION__, outbuf);
+
+	len = write (device_fd, outbuf, strlen(outbuf));
+	if ((size_t) len != strlen(outbuf) || len < 0) {
+		printf ("%s:%d could not write data to device:%s Error:%s\n", __FILE__, __LINE__,
+				device.c_str(), strerror(errno));
+		errormessage_display ((char *)"window-posctl", (char *)"WriteTTY",
+				(char *) "%s:%d could not write data to device:%s Error:%s\n", __FILE__, __LINE__,
+				device.c_str(), strerror(errno));
+	}
+
+	return 0;
+}
+
+int PosCtl::ReadTTY (char * inbuf, int length) {
+	ssize_t len;
+
+	// make device non-blocking
+	fcntl(device_fd, F_SETFL, fcntl(device_fd, F_GETFL) | O_NONBLOCK);
+	
+	len = read (device_fd, inbuf, length);
+
+	// somehow the first read sometimes fails, no idea why
+	if (len < 0 && (errno == EAGAIN || errno == EWOULDBLOCK)) {
+	  usleep(100000);
+	  len = read (device_fd, inbuf, length);
+	}
+	
+	if (len < 0) {
+		printf ("%s:%d could not read data from device:%s Error:%s\n", __FILE__, __LINE__,
+				device.c_str(), strerror(errno));
+		errormessage_display ((char *)"window-posctl", (char *)"ReadTTY",
+				(char *) "%s:%d could not read data from device:%s Error:%s\n", __FILE__, __LINE__,
+				device.c_str(), strerror(errno));
+		inbuf[0] = 0;
+	}
+	else {
+	  inbuf[len] = 0;
+	  printf ("%s:%d %s receive: '%s'\n", __FILE__, __LINE__, __FUNCTION__, inbuf);
+	}
+
+	// make device blocking
+	fcntl(device_fd, F_SETFL, fcntl(device_fd, F_GETFL) & ~O_NONBLOCK);
+
+	return 0;
+}
 
 int PosCtl::OutputWriteValue (int axis, double value) {
 	char outbuf[255];
-	ssize_t len;
 	printf ("%s:%d %s   Axis %d   Value:%f\n", __FILE__, __LINE__, __FUNCTION__, axis, value);
 
 	if (device_fd <= 0) if (OutputOpen() != 0) return -1;
@@ -677,46 +725,26 @@ int PosCtl::OutputWriteValue (int axis, double value) {
 	std::string s = setlocale(LC_ALL, NULL);
 	setlocale (LC_ALL, "C");
 
-	snprintf(outbuf, 254, ":R%c%c%08.4f#\n", (axis == 0 ? 'D' : 'R'),
-											(value < 0 ? '-' : '+'),
-											value);
+	snprintf(outbuf, 254, ":R%c%+09.4f#", (axis == 0 ? 'D' : 'R'), value);
 	outbuf[254] = 0;
 
 	// reset language setting to default
 	setlocale (LC_ALL, s.c_str());
 
-	printf ("%s:%d %s send: '%s'\n", __FILE__, __LINE__, __FUNCTION__, outbuf);
-
-	len = write (device_fd, outbuf, strlen(outbuf));
-	if ((size_t) len != strlen(outbuf) || len < 0) {
-		printf ("%s:%d could not write data to device:%s Error:%s\n", __FILE__, __LINE__,
-				device.c_str(), strerror(errno));
-		errormessage_display ((char *)"window-posctl", (char *)"OutputWriteValue",
-				(char *) "%s:%d could not write data to device:%s Error:%s\n", __FILE__, __LINE__,
-				device.c_str(), strerror(errno));
-	}
+	WriteTTY(outbuf);
+	ReadTTY(outbuf, sizeof(outbuf) - 1);
 
 	return 0;
 };
 
 int PosCtl::OutputWriteStop () {
 	char outbuf[255];
-	ssize_t len;
 
 	printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
 
-	snprintf (outbuf, 255, ":Q#, RT9#\n");
+	snprintf (outbuf, 255, ":Q#");
 	if (device_fd <= 0) if (OutputOpen() != 0) return -1;
-
-	len = write (device_fd, outbuf, strlen(outbuf));
-	if ((size_t) len != strlen(outbuf) || len < 0) {
-		printf ("%s:%d could not write data to device:%s Error:%s\n", __FILE__, __LINE__,
-				device.c_str(), strerror(errno));
-		errormessage_display ((char *)"window-posctl", (char *)"OutputWriteValue",
-				(char *) "%s:%d could not write data to device:%s Error:%s\n", __FILE__, __LINE__,
-				device.c_str(), strerror(errno));
-	}
-
+	WriteTTY(outbuf);
 
 	return 0;
 }
@@ -724,8 +752,8 @@ int PosCtl::OutputWriteStop () {
 int PosCtl::OutputWriteStart () {
 	printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
 
-	OutputWriteValue(0, 1.0);
-	OutputWriteValue(1, 1.0);
+	OutputWriteValue(0, 0.0);
+	OutputWriteValue(1, 0.0);
 
 	return 0;
 }