--- a/FXAnalyse.c	Fri Feb 21 18:42:29 2014 +0100
+++ b/FXAnalyse.c	Fri Feb 21 18:42:30 2014 +0100
@@ -1,6 +1,7 @@
 #include <tcpsupp.h>
 #include <utility.h>
 #include <ansi_c.h>
+#include <lowlvlio.h>
 #include <cvirte.h>		
 #include <userint.h>
 #include <formatio.h>
@@ -300,28 +301,34 @@
 static void write_data(const char *folder, const char *name, const char *id, 
 		const char *timestr, double utc, double *v, int nchan)
 {
+	int i, fd, len;
 	char line[1024];
 	char filename[FILENAME_MAX];
 	
 	// construct filename in the form folder\\id-name.txt
 	snprintf(filename, sizeof(filename), "%s\\%s-%s.txt", folder, id, name);
 	
-	int fd = OpenFile(filename, VAL_WRITE_ONLY, VAL_APPEND, VAL_ASCII);
-	switch (nchan)
-	{
-		case 1:
-			Fmt(line, "%s\t%f[p3]\t%f[p3]", 
-				timestr, utc, v[0]);
-			break;
-		case 4:
-			Fmt(line, "%s\t%f[p3]\t%f[p3]\t%f[p3]\t%f[p3]\t%f[p3]",
-				timestr, utc, v[0], v[1], v[2], v[3]);
-			break;
-		default:
-			strcpy(line, "?");
+	fd = open(filename, O_CREAT|O_WRONLY|O_APPEND);
+	if (fd < 0) {
+		logmessage(ERROR, "open data file %s: %s", filename, strerror(errno));
+		return;
 	}
-	WriteLine(fd, line, -1);
-	CloseFile(fd);
+	
+	// timestamp
+	len = snprintf(line, sizeof(line), "%s\t%.3f", timestr, utc);
+
+	// data channels
+	for (i = 0; i < nchan; i++)
+		len += snprintf(line + len, sizeof(line) - len, "\t%.3f", v[i]);
+	
+	// newline
+	line[len++] = '\r';
+	line[len++] = '\n';
+			
+	// write to file
+	write(fd, line, len);
+	
+	close(fd);
 }