diff --git a/site_ansto/hardsup/sct_lfprot.c b/site_ansto/hardsup/sct_lfprot.c
index 7ed7f734..3733959a 100644
--- a/site_ansto/hardsup/sct_lfprot.c
+++ b/site_ansto/hardsup/sct_lfprot.c
@@ -145,17 +145,20 @@ int LFGenReading(Ascon *a)
   // Read HEAD info
   do {
     ret = AsconReadChar(a->fd, &chr);
-    if(ret<0) {
-      AsconError(a, "AsconReadChar failed:", errno);
+    if(ret<=0) {
+      AsconError(a, "AsconReadChar failed:", 0);
+      a->state = AsconReadDone;
       return 0; 
+    } else {
+      HEAD  = (BYTE)chr;
     }
-    HEAD  = (BYTE)chr;
   } while (HEAD!=0x96);
  
   // read LEN info
   ret = AsconReadChar(a->fd, &chr);
-  if(ret<0) {
-    AsconError(a, "AsconReadChar failed:", errno); 
+  if(ret<=0) {
+    AsconError(a, "AsconReadChar failed:", 0); 
+    a->state = AsconReadDone;
     return 0; 
   }
   LEN = (BYTE)chr;
@@ -173,8 +176,8 @@ int LFGenReading(Ascon *a)
   // read all other chars
   while(ind<LEN+2) {
     ret = AsconReadChar(a->fd, &chr);
-    if (ret < 0) {
-      AsconError(a, "AsconReadChar failed:", errno);
+    if (ret <= 0) {
+      AsconError(a, "AsconReadChar failed:", 0);
       a->state = AsconReadDone;
       return 0;
     }