Hello:

I have experienced exactly the same problem. Every time I try to connect a TCP Modbus client (Modscan32) to my LOGO, this terminates the TCP/IP connection inmediatelly.

Any idea about the issue? I am only trying to read the I/O.

Nothing found in other threads.   I am able to connect the same Modbus client to other devices.

Thanks and regards 

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Split from ModBus TCP connection with Logo.

I answer myself!

The default TCP port is 510!!! (instead of 502).

Now the Modbus TCP commmunication is working ok.

Regards

Maybe Modscan32 uses port 510 as default, but normally port 502 is defined as the reserved and first port number for Modbus. If you create several Modbus clients in the Logo, the default numbers are 502, 503, 504 and so on. Sure it is possible to use any other free port number, if the same number is used on both sides.

I think, it would also be possible to change the port number in Modscan32.

Regards, Scorp

Hello:

Of course the port can be changed at Modscan32, by default is 502, but selecting this port my LOGO refuses the connection. Switching to port 510, the LOGO is connecting properly. I have also tried with other Modbus clients and it is the same: attempts made through the 502 are inmediately refused and the 510 works fine.

Regards

Hello,
you obviously parameterized port 510 at LOGO.

Regards,
Kaulquappe

ivanusis

Hello:

Of course the port can be changed at Modscan32, by default is 502, but selecting this port my LOGO refuses the connection. Switching to port 510, the LOGO is connecting properly. I have also tried with other Modbus clients and it is the same: attempts made through the 502 are inmediately refused and the 510 works fine.

Regards

 Have you tested Modscan32 AND Logo both with port number 502 ? Then it is possible, that port number 502 is blocked by any other device. But it doesn't matter, if you have a stable connection with 510.

Regards, Scorp

 Hi there, sorry to ressurect this from the grave but i am having the same issue.

Port 502 is specified on the Logosoft..as master..

Modscan and cas can only read data when specified 510.. everything is great but why 510?

Logo 8.3 V1.83.01

This logo is talking to schneider m580

Kaulquappe

Hello,
you obviously parameterized port 510 at LOGO.

Regards,
Kaulquappe

Hello Forum!

Yesterday I faced the same isue with Modbus Port 502.

A delivered project that had been working for over a year out of a sudden Logo Modbus TCP/IP was lost and I think something was blocking the port 502, maybe a firewall of Unify router that exists.

Never the less the Modbus Server of iridium that I had been using in this project couldn't connect to 502 of logo as programmed. Via Modbus Master radzio I figured out that the logo was responding on port 510 as mentioned earlier and I set iridium modbus server to port 510 and worked fine.

I would like to know why 510 responded and not 502, 503 that I had been expecting?

Could someone provide an answer?

Thanks in advance!