TCP unexpected message length

dirtbikersteve

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Jul 14, 2017, 10:46:05 AM7/14/17

to libmodbus

Hey all im trying to talk to a sealevel IO device over modbus TCP. However i'm receiving back an unexpected number of bytes:

[00][01][00][00][00][06][01][02][00][00][00][08]

Waiting for a confirmation...

Message length not corresponding to the computed length (11 != 10)

<00><01><00><00><00><05><00><01><02><01><00>

[14-07-2017 10:41:17] [ERROR] read failed: Invalid data

Now to me the response seems perfectly valid (7 byte header, then the PDU packet). PDU packet containing the the bytes slave ID, data length of 2, then the two data bytes. What is wrong with this response?

dirtbikersteve

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Jul 14, 2017, 10:47:14 AM7/14/17

to libmodbus

According to this site the response is valid as well. http://www.simplymodbus.ca/TCP.htm

dirtbikersteve

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Jul 17, 2017, 10:23:52 AM7/17/17

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Anyone?

Stéphane Raimbault

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Jul 25, 2017, 4:16:55 AM7/25/17

to libm...@googlegroups.com

The data length should coded on 2 bytes in TCP.

https://github.com/stephane/libmodbus/blob/master/src/modbus-tcp.c#L120

Le 17 juillet 2017 à 16:23, dirtbikersteve <stevem...@gmail.com> a écrit :

Anyone?
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