Hi Everyone,
I am using a plc4x modbus driver to read data from a modbus device but i am
left with an exception. But while reading data from the ModbusPal virtual
device I am getting the output. The java code and the error message is
given below.
I need help from this community to complete my POC.
Java code.
import org.apache.plc4x.java.PlcDriverManager;
import org.apache.plc4x.java.api.PlcConnection;
import org.apache.plc4x.java.api.messages.PlcReadRequest;
import org.apache.plc4x.java.api.messages.PlcReadResponse;
import org.apache.plc4x.java.api.types.PlcResponseCode;
import java.util.concurrent.CompletableFuture;
public class modbus {
public static void main(String[] args) throws Exception {
System.out.println("started");
String connectionString =
"modbus:tcp://192.168.4.163:4001?unit-identifier=2";
try {
PlcConnection plcConnection = new
PlcDriverManager().getConnection(connectionString);
if (!plcConnection.getMetadata().canRead()) {
System.out.println("This connection doesn't support reading.");
return;
}
PlcReadRequest.Builder builder = plcConnection.readRequestBuilder();
builder.addItem("tag1","holding-register:101");
// builder.addItem("tag2","holding-register:1[3]");
PlcReadRequest readRequest = builder.build();
CompletableFuture<? extends PlcReadResponse> asyncResponse
= readRequest.execute();
asyncResponse.whenComplete((response, throwable) -> {
System.out.println("response :"+response.toString() );
for (String fieldName : response.getFieldNames()) {
if (response.getResponseCode(fieldName) ==
PlcResponseCode.OK){
int registerValues =
response.getNumberOfValues(fieldName);
if (registerValues == 1){
System.out.println(fieldName +" : "+
response.getObject(fieldName));
}
else {
for (int i = 0; i< registerValues;i++){
System.out.println(fieldName + i +" :
" + response.getObject(fieldName,i));
}
}
}
else {
System.out.println("Error[" + fieldName+ "]:
"+ response.getResponseCode(fieldName).name());
}
}
});
} catch (Exception e) {
System.out.println("Something went wrong."+e);
}
System.out.println("Execution completed");
}
}
Output:
started
SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further
details.
Execution completed
Aug 12, 2020 3:05:02 PM io.netty.channel.DefaultChannelPipeline
onUnhandledInboundException
WARNING: An exceptionCaught() event was fired, and it reached at the tail
of the pipeline. It usually means the last handler in the pipeline did not
handle the exception.
io.netty.handler.codec.DecoderException:
org.apache.plc4x.java.api.exceptions.PlcRuntimeException: Unexpected
response type ModbusPDUReadHoldingRegistersResponse
at
io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:98)
at
io.netty.handler.codec.MessageToMessageCodec.channelRead(MessageToMessageCodec.java:111)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at
io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at
io.netty.handler.codec.ByteToMessageDecoder.fireChannelRead(ByteToMessageDecoder.java:321)
at
io.netty.handler.codec.ByteToMessageDecoder.channelRead(ByteToMessageDecoder.java:295)
at
io.netty.handler.codec.ByteToMessageCodec.channelRead(ByteToMessageCodec.java:103)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at
io.netty.channel.AbstractChannelHandlerContext.fireChannelRead(AbstractChannelHandlerContext.java:357)
at
io.netty.channel.DefaultChannelPipeline$HeadContext.channelRead(DefaultChannelPipeline.java:1410)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:379)
at
io.netty.channel.AbstractChannelHandlerContext.invokeChannelRead(AbstractChannelHandlerContext.java:365)
at
io.netty.channel.DefaultChannelPipeline.fireChannelRead(DefaultChannelPipeline.java:919)
at
io.netty.channel.nio.AbstractNioByteChannel$NioByteUnsafe.read(AbstractNioByteChannel.java:163)
at
io.netty.channel.nio.NioEventLoop.processSelectedKey(NioEventLoop.java:714)
at
io.netty.channel.nio.NioEventLoop.processSelectedKeysOptimized(NioEventLoop.java:650)
at
io.netty.channel.nio.NioEventLoop.processSelectedKeys(NioEventLoop.java:576)
at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:493)
at
io.netty.util.concurrent.SingleThreadEventExecutor$4.run(SingleThreadEventExecutor.java:989)
at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
at
io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: org.apache.plc4x.java.api.exceptions.PlcRuntimeException:
Unexpected response type ModbusPDUReadHoldingRegistersResponse
at
org.apache.plc4x.java.modbus.protocol.ModbusProtocolLogic.toPlcValue(ModbusProtocolLogic.java:240)
at
org.apache.plc4x.java.modbus.protocol.ModbusProtocolLogic.lambda$read$2(ModbusProtocolLogic.java:112)
at
org.apache.plc4x.java.spi.Plc4xNettyWrapper.decode(Plc4xNettyWrapper.java:154)
at
io.netty.handler.codec.MessageToMessageCodec$2.decode(MessageToMessageCodec.java:81)
at
io.netty.handler.codec.MessageToMessageDecoder.channelRead(MessageToMessageDecoder.java:88)
... 23 more
When used another Modbus master Simulator by name - modpoll to cross
verify , getting the correct value as shown below.
./modpoll -m tcp -a 2 -r 101 -c 1 -t 4:float -p 4001 192.168.4.163
modpoll 3.9 - FieldTalk(tm) Modbus(R) Master Simulator
Copyright (c) 2002-2020 proconX Pty Ltd
Visit https://www.modbusdriver.com for Modbus libraries and tools.
Protocol configuration: MODBUS/TCP, FC3
Slave configuration...: address = 2, start reference = 101, count = 1
Communication.........: 192.168.4.163, port 4001, t/o 1.00 s, poll rate
1000 ms
Data type.............: 32-bit float, output (holding) register table
-- Polling slave... (Ctrl-C to stop)
[101]: 2353.341064
-- Polling slave... (Ctrl-C to stop)
Reply time-out!
-- Polling slave... (Ctrl-C to stop)
Reply time-out!
-- Polling slave... (Ctrl-C to stop)
[101]: 2353.341064
-- Polling slave... (Ctrl-C to stop)
[101]: 2353.341064
-- Polling slave... (Ctrl-C to stop)
[101]: 2353.341064
--
Thanks and Regards;
Syed Kefayath
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