cont

test_write.c

@@ -18,7 +18,10 @@
 
 #define DEBUG(f_, ...) do { fprintf(stderr,"[DEBUG:%d]\"",__LINE__);fprintf(stderr,(f_), __VA_ARGS__);fprintf(stderr,"\"\n");} while(0);
 
-int subdev = 1;			/* change this to your input subdevice */
+#define WHERE  fprintf(stderr,"[DEBUG:%d]\"",__LINE__)
+
+int subdevr = 0;			/* change this to your input subdevice */
+int subdevw = 1;			/* change this to your input subdevice */
 int chan = 0;			/* change this to your channel */
 int range = 0;			/* more on this later */
 int aref = AREF_GROUND;		/* more on this later */
@@ -30,42 +33,50 @@ int main(int argc, char *argv[])
 	;
 	double physical_value;
 	int retval;
-	comedi_range *range_info;
-	lsampl_t maxdata;
+	comedi_range *range_infor;
+	lsampl_t maxdatar;
+	comedi_range *range_infow;
+	lsampl_t maxdataw;
 
 	device = comedi_open(filename);
 	if (device == NULL) {
 		comedi_perror(filename);
 		return 1;
 	}
-	range_info = comedi_get_range(device, subdev, chan, range);
-	maxdata = comedi_get_maxdata(device, subdev, chan);
+	range_infor = comedi_get_range(device, subdevr, chan, range);
+	maxdatar = comedi_get_maxdata(device, subdevr, chan);
+	range_infow = comedi_get_range(device, subdevw, chan, range);
+	maxdataw = comedi_get_maxdata(device, subdevw, chan);
+
 	comedi_set_global_oor_behavior(COMEDI_OOR_NAN);
-	double userdata=10;
-	double sign=1;
-	double shift=0.001;
-	double max=10;
+
 	for(;;)
 		{
-		//DEBUG("userdata = %g",userdata);
-		lsampl_t data =  comedi_from_phys(userdata, range_info, maxdata);
-		//DEBUG("data = %d",data);
-		retval = comedi_data_write(device, subdev, chan, range, aref,
-					  data);
+		lsampl_t data;
+		retval = comedi_data_read(device, subdevr, chan, range, aref,
+					  &data);
+
 		if (retval < 0) {
+			WHERE;
 			comedi_perror(filename);
 			return 1;
 			}
+		double physical_value = comedi_to_phys(data, range_infor, maxdatar);
+		
+		physical_value=-physical_value;
+				
 
-		userdata +=(sign*shift);
-		if(userdata > max) {
-			userdata= max;
-			sign=-sign;
-			}
-		else if(userdata < -max){
-			userdata= -max;
-			sign=-sign;
+		data = comedi_from_phys(physical_value, range_infow, maxdataw);
+		
+
+		retval = comedi_data_write(device, subdevw, chan, range, aref,
+					  data);
+		if (retval < 0) {
+			WHERE;
+			comedi_perror(filename);
+			return 1;
 			}
+
 		}
 	return 0;
 }