Read 4x registers

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William MARTIN

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Sep 16, 2015, 5:57:37 AM9/16/15
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Hi,

I want to use the libmodbus to read register with high address, like 0x40211.
How to do that ?

This is the function 23 (17Hex) Read/Write 4X Registers in the official documentation of modbus.

Best regards,
William

Torello Querci

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Sep 16, 2015, 6:18:03 AM9/16/15
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Are you sure about register address?
In my personal experience high address indicate command 04 (read input register) for register 211.


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Olivier Barthelemy

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Sep 16, 2015, 7:06:15 AM9/16/15
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On some devices, what's displayed as adresses 40XXX is actually read by normal read function with adress XXX
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Bodo Meissner

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Sep 16, 2015, 7:50:03 AM9/16/15
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Zitat von William MARTIN <wys...@gmail.com>:

> I want to use the libmodbus to read register with high address, like
> 0x40211.
[...]
> This is the function 23 (17Hex) Read/Write 4X Registers in the official
> documentation of modbus.

Hello William,

see
http://libmodbus.org/docs/v3.1.2/modbus_write_and_read_registers.html
"The function uses the Modbus function code 0x17 (write/read registers)."

Bodo


William MARTIN

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Sep 16, 2015, 7:52:21 AM9/16/15
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Many thanks,

I just need to ignore the 40 prefix and it's works fine.

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