diff --git a/detect.h b/detect.h
index 3b56a2c..9d20ccf 100644
--- a/detect.h
+++ b/detect.h
@@ -63,8 +63,8 @@ class PosCtl {
 		void CalibModeAxis(int x, int y);
 		void CalibModeFinish();
 
-		void OutputClose();
-		void OutputOpen();
+		int OutputClose();
+		int OutputOpen();
 	public:
 		PosCtl();
 		~PosCtl() {};
@@ -95,9 +95,9 @@ class PosCtl {
 		std::string GetDevice() { return device; };
 
 		void Loop (int posx, int posy);
-		void OutputWriteValue (int axis, double value);
-		void OutputWriteStop (int axis);
-		void OutputWriteStart (int axis);
+		int OutputWriteValue (int axis, double value);
+		int OutputWriteStop (int axis);
+		int OutputWriteStart (int axis);
 };
 
 
diff --git a/posctl.cc b/posctl.cc
index 5c909da..449daa4 100644
--- a/posctl.cc
+++ b/posctl.cc
@@ -606,16 +606,18 @@ void PosCtl::SetDevice (std::string d) {
 };
 
 
-void PosCtl::OutputClose() {
+int PosCtl::OutputClose() {
 	printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
 	if (device_fd > 0) close(device_fd);
 	device_fd = -1;
+
+	return 0;
 };
 
 
-void PosCtl::OutputOpen() {
+int PosCtl::OutputOpen() {
 	printf ("%s:%d %s\n", __FILE__, __LINE__, __FUNCTION__);
-	if (device_fd > 0) return;
+	if (device_fd > 0) return 0;
 
 	device_fd = open (device.c_str(), O_RDWR);
 	if (device_fd < 0) {
@@ -623,16 +625,18 @@ void PosCtl::OutputOpen() {
 				device.c_str(), strerror(errno));
 		errormessage_display ((char *)"window-posctl", (char *)"OutputOpen",
 				(char*)"%s:%d could not open device:%s Error:%s\n", __FILE__, __LINE__, device.c_str(), strerror(errno));
+		return -1;
 	}
+	return 0;
 };
 
 
-void PosCtl::OutputWriteValue (int axis, double value) {
+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) OutputOpen();
+	if (device_fd <= 0) if (OutputOpen() != 0) return -1;
 
 	//
 	// save language setting and set to plain C
@@ -654,21 +658,25 @@ void PosCtl::OutputWriteValue (int axis, double value) {
 		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",
-				"%s:%d could not write data to device:%s Error:%s\n", __FILE__, __LINE__,
+				(char *) "%s:%d could not write data to device:%s Error:%s\n", __FILE__, __LINE__,
 				device.c_str(), strerror(errno));
 	}
+
+	return 0;
 };
 
-void PosCtl::OutputWriteStop (int axis) {
+int PosCtl::OutputWriteStop (int axis) {
 	printf ("%s:%d %s   Axis %d\n", __FILE__, __LINE__, __FUNCTION__, axis);
 
-	if (device_fd <= 0) OutputOpen();
+	if (device_fd <= 0) if (OutputOpen() != 0) return -1;
+	return 0;
 }
 
-void PosCtl::OutputWriteStart (int axis) {
+int PosCtl::OutputWriteStart (int axis) {
 	printf ("%s:%d %s   Axis %d\n", __FILE__, __LINE__, __FUNCTION__, axis);
 
-	if (device_fd <= 0) OutputOpen();
+	if (device_fd <= 0) if (OutputOpen() != 0) return -1;
+	return 0;
 }