Handle heartbeat messages (fix #4824)

1 files changed, 7 insertions, 2 deletions

diff --git a/src/main/java/org/traccar/protocol/NavtelecomFrameDecoder.java b/src/main/java/org/traccar/protocol/NavtelecomFrameDecoder.java
index 0fb82528b..2ab7d11a9 100644
--- a/src/main/java/org/traccar/protocol/NavtelecomFrameDecoder.java
+++ b/src/main/java/org/traccar/protocol/NavtelecomFrameDecoder.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2021 Anton Tananaev (anton@traccar.org)
+ * Copyright 2021 - 2022 Anton Tananaev (anton@traccar.org)
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -30,7 +30,12 @@ public class NavtelecomFrameDecoder extends BaseFrameDecoder {
     protected Object decode(
             ChannelHandlerContext ctx, Channel channel, ByteBuf buf) throws Exception {
 
-        if (buf.getByte(buf.readerIndex()) == '@') {
+        if (buf.getByte(buf.readerIndex()) == 0x7f) {
+
+            buf.skipBytes(1);
+            return null;
+
+        } else if (buf.getByte(buf.readerIndex()) == '@') {
 
             int length = buf.getUnsignedShortLE(12) + 12 + 2 + 2;
             if (buf.readableBytes() >= length) {