Waiting for a confirmation... ERROR Connection timed out: select

[franco bustaffa]

I am trying to interface a TCP ModBus device  with unit-test-client.c simplified. The program now contains only a modbus_write_register. I would like to set a register value only. I can connect successfully the device but the modbus_write_register function fails with 

“

[00][01][00][00][00][06][FF][06][00][69][00][01]

Waiting for a confirmation...

ERROR Connection timed out: select

“

Of course my test  program works locally (127.0.0.1) with the libmodbus server test program.

Of course I have increased the timeout to 3 sec. 

I think that my error is in some environment setting.

May you help me?

Ciao Franco

[Stéphane Raimbault]

It's frequent that some devices aren't Modbus compliant and it's required in this case to use modbus_set_slave() to set the slave ID of the remote device before sending the request (I should add this information to the documentation).

http://libmodbus.org/docs/v3.1.1/modbus_set_slave.html

http://sralab.com/2011/04/27/not-compliant-device-can-be-time-consuming/

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[franco bustaffa]

Thank you for the reply.

I have inserted the modbus_set_slave() function  with the special value MODBUS_TCP_SLAVE (0xFF) successfully. But the result was the same.

But I remember that this device accepts slave with ID equal to 1 and not 0xFF: I have changed 0xFF with 1 and it works! 

May be it is an implementation error and I will inform the producer about it (I think the producer already know it).

Anyway with your help I solved the problem!

For the libmodbus community the device interfaced is ECOMM EC1. The EC1 is an 802.15.4 PAN Coordinator of a wireless sensor network.

Thank you again.

Ciao Franco

[Stéphane Raimbault]

So I really should document this common issue!

https://github.com/stephane/libmodbus/issues/219

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[萌喵喵]

I also found this problem. I connect a recorder via ethernet. If I use "modbus_set_debug", the program would dump this error message. If I don't turn off "modbus_set_debug", everything will be fine. And the recorder can give me the correct register value.

regards

franco bustaffa於 2014年6月5日星期四 UTC+8下午10時57分38秒寫道：