Schneider Electric Modbus Plus Network Bridge Multiplexer none Manual do Utilizador descarregar pdf (Página 7)

Chapter 3 Connecting to a Controller

Modbus communications by modem l 41

3. Set Modbus communication parameters for your network.

Ÿ The Modbus Port setting must show the computer port connected

to the modem; otherwise, NxT won’t be able to locate it.

v For more information, see the Modbus table on page38.

Ÿ The Modbus configuration must send exactly 10 bits per data

package to your modem.

Modems generally expect 10 bits in a data package; however, the

Modbus defaults (Even parity, RTU mode, and one stop bit) send

11 bits per package.

Change the Modbus settings to provide 10 bits per data package or

NxT will not be able to communicate with the modem.

Alternatively, if your modem supports large data packages, you

can set its DIP switches to allow 11 bits per data package (see your

modem’s manual).

These Modbus configurations provide 10 bits per data package:

4. Choose settings for your modem.

The controller must have the same Modbus settings as the computer. Set

Modbus parameters for your PLC with the Ports tab of the Controller

Configuration window.

v For more information, see “Controller configuration - Ports tab” on page62.

Parameters ASCII Mode ASCII Mode RTU Mode

Start Bit 1 bit 1 bit 1 bit

Data 7 bits 7 bits 8 bits

Stop Bits: 1 1 bit 1 bit

2 2 bits

Parity: None 0 bits 0 bits

Odd or Even 1 bit

Total 10 bits 10 bits 10 bits

1 2 3 4 5 6 7 8 9 10 11 12 ... 19 20

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Schneider Electric Modbus Plus Network Bridge Multiplexer none Manual do Utilizador Página 7