ModbusTCP to ModbusRTU bridge with on-device ModbusRTU simulator

[javiergentoo]

Hi Before, thank you very much for the contribution.

I have using this example to connect with a real RTU slave and I ask from tcp modbus. I can see than when I send a request from tcp modbus, it go thrown the RTU Modbus and the device answer from Serial port ok. but the "tcp.rawResponce(srcIp, data, len, slaveRunning);" do not send the data back to the TCP. I have done a for into the data and the information is there, but I don't receive any into the tcp request.

I don't use the sym inside the example, I am using the Serial1 connecting to the slave RTU.

The RTU is working because I am receiving the request from tcp modbus and go on to RTU modbus. But in the PC I receive empty.

Into ESP32:

• TCP IP: 192.168.1.155 Fn: 04, len: 5 This is the for of the data: 4 0 5 0 12 120

And I receive this order message:

Modbus result: E4, Mem: 270660

What could I do wrong ?

[javiergentoo]

Part of the code:

if (src->unitId) { tcp.setTransactionId(transRunning); // Set transaction id as per incoming request

uint16_t succeed = tcp.rawResponce(src->ipaddr, data, len, slaveRunning);

for(int i = 0; i <= len; i++) {
  Serial.print(i);
  Serial.print(": ");
  Serial.println(data[i]);   // I have add this for watch the data and the data are coming perfect
}

output from real slave: TCP IP: 192.168.1.155 Fn: 04, len: 5 0: 4 1: 0 2: 5 3: 0 4: 10 5: 120 fail:0 ----> this output come from function "Modbus::ResultCode cbRtuRaw(uint8_t data, uint8_t len, void custom) RTU Slave: 1, Fn: 04, len: 22, Response TCP IP: 192.168.1.155

But I received an array empty in the PC:

[emelianov]

Take a look fixed TCP-to-RTU-Simulator example changes I've just pushed. Also note that response to TCP client is send from cbRtuRaw not from cbTcpRaw.

[javiergentoo]

Hi Alexander Thank you very much for your contribution, now it is working perfect. only it has a error in compilation because it has a extra parenthesis in line 61:

-before: tcp.errorResponce(IPAddress((src->ipaddr), (Modbus::FunctionCode)data[0], Modbus::EX_SLAVE_DEVICE_BUSY);

-after: tcp.errorResponce(IPAddress(src->ipaddr), (Modbus::FunctionCode)data[0], Modbus::EX_SLAVE_DEVICE_BUSY);

But it is working perfect. Thanks

[javiergentoo]

Hi Alexander I am testing the code and I have found a bug so I am trying to find where is: I have a slave RTU modbus connect with id=1, I don the tcp modbus with this id and the tcp answer perfect. But if I do the request with id=2 and this one not responde, the tcp will disconnect and do not recover again.

I will try to find where is the problem.

the console log show always:

TCP IP in - 192.168.1.155 Fn: 04, len: 5 Modbus result: E4, Mem: 266436 TCP IP in - 192.168.1.155 Fn: 04, len: 5 TCP IP in - 192.168.1.164 Fn: 04, len: 5 TCP IP in - 192.168.1.164 Fn: 04, len: 5 TCP IP in - 192.168.1.164 Fn: 04, len: 5 TCP IP in - 192.168.1.164 Fn: 04, len: 5 TCP IP in - 192.168.1.164 Fn: 04, len: 5 TCP IP in - 192.168.1.164 Fn: 04, len: 5 TCP IP in - 192.168.1.164 Fn: 04, len: 5 TCP IP in - 192.168.1.164 Fn: 04, len: 5

Thanks

[javiergentoo]

Hi Alexander

I have add this two lines and know it is working:

if (transRunning) { // Note that we can't process new requests from TCP-side while waiting for responce from RTU-side. tcp.setTransactionId(src->transactionId); // Set transaction id as per incoming request tcp.errorResponce(IPAddress(src->ipaddr), (Modbus::FunctionCode)data[0], Modbus::EX_SLAVE_DEVICE_BUSY); transRunning = 0; slaveRunning = 0; return Modbus::EX_SLAVE_DEVICE_BUSY; }

[emelianov]

Great, thanks. I'll add your correction to the example.

[emelianov]

I've updated the example code with slightly more correct solution than provided by your (but your direction was right).

[javiergentoo]

Thank you very much for your help

[javiergentoo]

Hi Emelianov

I have changed the example like your modification, but it doesn't work. When I request an address where it is not present and return again to the address present the tcp is disconnect.

With this lines works perfect:

if (transRunning) { // Note that we can't process new requests from TCP-side while waiting for responce from RTU-side. tcp.setTransactionId(src->transactionId); // Set transaction id as per incoming request tcp.errorResponce(IPAddress(src->ipaddr), (Modbus::FunctionCode)data[0], Modbus::EX_SLAVE_DEVICE_BUSY); transRunning = 0; slaveRunning = 0; return Modbus::EX_SLAVE_DEVICE_BUSY; }