2 files changed, 25 insertions, 2 deletions
diff --git a/src/org/traccar/protocol/UlbotechProtocolDecoder.java b/src/org/traccar/protocol/UlbotechProtocolDecoder.java
index 97912e128..b5d60431d 100644
--- a/src/org/traccar/protocol/UlbotechProtocolDecoder.java
+++ b/src/org/traccar/protocol/UlbotechProtocolDecoder.java
@@ -22,6 +22,7 @@ import org.traccar.BaseProtocolDecoder;
 import org.traccar.Context;
 import org.traccar.DeviceSession;
 import org.traccar.helper.BitUtil;
+import org.traccar.helper.Checksum;
 import org.traccar.helper.DateBuilder;
 import org.traccar.helper.ObdDecoder;
 import org.traccar.helper.Parser;
@@ -340,8 +341,27 @@ public class UlbotechProtocolDecoder extends BaseProtocolDecoder {
         ChannelBuffer buf = (ChannelBuffer) msg;
 
         if (buf.getUnsignedByte(buf.readerIndex()) == 0xF8) {
+
+            if (channel != null) {
+                ChannelBuffer response = ChannelBuffers.dynamicBuffer();
+                response.writeByte(0xF8);
+                response.writeByte(DATA_GPS);
+                response.writeByte(0xFE);
+                response.writeShort(buf.getShort(response.writerIndex() - 1 - 2));
+                response.writeShort(Checksum.crc16(Checksum.CRC16_XMODEM, response.toByteBuffer(1, 4)));
+                response.writeByte(0xF8);
+                channel.write(response);
+            }
+
             return decodeBinary(channel, remoteAddress, buf);
         } else {
+
+            if (channel != null) {
+                channel.write(ChannelBuffers.copiedBuffer(String.format("*TS01,ACK:%04X#",
+                        Checksum.crc16(Checksum.CRC16_XMODEM, buf.toByteBuffer(1, buf.writerIndex() - 2))),
+                        StandardCharsets.US_ASCII));
+            }
+
             return decodeText(channel, remoteAddress, buf.toString(StandardCharsets.US_ASCII));
         }
     }
diff --git a/test/org/traccar/protocol/UlbotechProtocolDecoderTest.java b/test/org/traccar/protocol/UlbotechProtocolDecoderTest.java
index c76912f18..cb2a06ba9 100644
--- a/test/org/traccar/protocol/UlbotechProtocolDecoderTest.java
+++ b/test/org/traccar/protocol/UlbotechProtocolDecoderTest.java
@@ -10,6 +10,9 @@ public class UlbotechProtocolDecoderTest extends ProtocolTest {
 
         UlbotechProtocolDecoder decoder = new UlbotechProtocolDecoder(new UlbotechProtocol());
 
+        verifyNothing(decoder, buffer(
+                "*TS01,353323081464660#"));
+
         verifyAttributes(decoder, buffer(
                 "*TS01,868323025245751,134955140317,WFE:0#"));
 
@@ -40,8 +43,8 @@ public class UlbotechProtocolDecoderTest extends ProtocolTest {
         verifyPosition(decoder, binary(
                 "f8010103515790566431569e5fbb9d010e015ee2b906bde4a000000000009f03040a4000000404000115fe05060340173f22030711310583410c0000310d00312f834131000008040000b78c09077320290082c021100101120af8"));
 
-        verifyNothing(decoder, binary(
-                "2a545330312c33353430343330353133383934363023"));
+        verifyNothing(decoder, buffer(
+                "*TS01,354043051389460#"));
 
         verifyPosition(decoder, binary(
                 "f8010108679650230646339de69054010e015ee17506bde2c60000000000ac0304024000000404000009f705060390181422170711310583410c0000310d00312f834131018608040003130a100101136cf8"));