diff --git a/code/application/source/sf_app/code/source/ttyusb/sf_hal_ttyusb.c b/code/application/source/sf_app/code/source/ttyusb/sf_hal_ttyusb.c
index 68274422b..d1626dcb0 100755
--- a/code/application/source/sf_app/code/source/ttyusb/sf_hal_ttyusb.c
+++ b/code/application/source/sf_app/code/source/ttyusb/sf_hal_ttyusb.c
@@ -430,23 +430,25 @@ SINT32 sf_hal_ttyusb2_read_buf(SF_TTY_DATA_TYPE_S *recv)
     TimeoutVal.tv_sec  = 0;
     TimeoutVal.tv_usec = (recv->waitMs)*1000;
 
-    while(waitTime--)
+    while(waitTime)
     {
         s32ret = select(TtyUSB2Fd + 1, &read_fds, NULL, NULL, &TimeoutVal);
         if (s32ret > 0) {
             if (FD_ISSET(TtyUSB2Fd, &read_fds)) {
                 s32ret = read(TtyUSB2Fd, recv->data+dataL, recv->lenMax);
                 dataL += strlen(recv->data);
-                if ((((dataL) >= (recv->len)) && (strstr(recv->data, recv->cmp))) || (strstr(recv->data, recv->cmperr))) {
+                if (((dataL) >= (recv->len)) || (strstr(recv->data, recv->cmp)) || (strstr(recv->data, recv->cmperr))) {
                     break;
                 }
             }
         } 
         else if (s32ret < 0) {
+            waitTime--;
             MLOGE(" select failed\n");
             continue;
         } 
         else if (0 == s32ret) {
+            waitTime--;
             MLOGW("FIFO select timeout [%d]\n",waitTime);
             continue;
         }