Shan Xiao

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10 years, 7 months ago.

modbus: modpoll

Hi all,

I'm not sure if this is the right place to ask this question.

I wonder if anyone has ever used the "modpoll" tool before as a Modbus master polling tool? http://www.modbusdriver.com/modpoll.html

I'm testing it on my Modbus slave device whose address is based on PDU addressing. (Starting address is 0)

In the modpoll setup, we can use "-0" to set the first reference as 0 instead of 1.

However, the start reference parameter ("-r") is defined between 1-65536.

In this case, I couldn't get the value at register 0.

I tried to set the "-r" parameter 0 but it's invalid.

I tried to contact the modpoll website service but haven't got any reply from them.

Hope someone here could help. Thanks!

FYI:

Usage: modpoll [options] serialport|host
Arguments:
serialport    Serial port when using Modbus ASCII or Modbus RTU protocol
              COM1, COM2 ...                on Windows
              /dev/ttyS0, /dev/ttyS1 ...    on Linux
              /dev/ser1, /dev/ser2 ...      on QNX
host          Host name or dotted ip address when using MODBUS/TCP protocol
General options:
-m ascii      Modbus ASCII protocol
-m rtu        Modbus RTU protocol (default)
-m tcp        MODBUS/TCP protocol
-m enc        Encapsulated Modbus RTU over TCP
-a #          Slave address (1-255, 1 is default)
-r #          Start reference (1-65536, 100 is default)
-c #          Number of values to poll (1-100, 1 is default)
-t 0          Discrete output (coil) data type
-t 1          Discrete input data type
-t 3          16-bit input register data type
-t 3:hex      16-bit input register data type with hex display
-t 3:int      32-bit integer data type in input register table
-t 3:mod      32-bit module 10000 data type in input register table
-t 3:float    32-bit float data type in input register table
-t 4          16-bit output (holding) register data type (default)
-t 4:hex      16-bit output (holding) register data type with hex display
-t 4:int      32-bit integer data type in output (holding) register table
-t 4:mod      32-bit module 10000 type in output (holding) register table
-t 4:float    32-bit float data type in output (holding) register table
-i            Slave operates on big-endian 32-bit integers
-f            Slave operates on big-endian 32-bit floats
-1            Poll only once, otherwise poll every second
-e            Use Daniel/Enron single register 32-bit mode
-0            First reference is 0 (PDU addressing) instead 1
Options for MODBUS/TCP:
-p #          TCP port number (502 is default)
Options for Modbus ASCII and Modbus RTU:
-b #          Baudrate (e.g. 9600, 19200, ...) (9600 is default)
-d #          Databits (7 or 8 for ASCII protocol, 8 for RTU)
-s #          Stopbits (1 or 2, 1 is default)
-p none       No parity
-p even       Even parity (default)
-p odd        Odd parity
-4 #          RS-485 mode, RTS on while transmitting and another # ms after
-o #          Time-out in seconds (0.01 - 10.0, 1.0 s is default)
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