ElmoMC Multi-Axis Motion Controller-Maestro - Manual (Page 222)

Maestro Software Manual Ethernet/IP Communication
MAN-MASSW (Ver. Q)
12-2
12.1 Master (Client) functionality implementation
The MODBUS master object provides connectivity to MODBUS slave compatible devices
and applications. The MODBUS Master can have one of following types (Fig.12-2):
Figure 12-2: MODBUS Master types
12.1.1 Ethernet media
12.1.1.1 TCP communication parameters
• MODBUS address- In the “MODBUS Messaging on TCP/IP Implementation
Guide” the MODBUS slave address (Unit Identifier) is described as:
o
The ‘Unit Identifier’ is used to communicate via devices such as bridges,
routers and gateways using a single IP address to support multiple
independent MODBUS end units. The destination IP address identifies the
bridge itself and the bridge uses the MODBUS ‘Unit Identifier’ to forward
the request to the right slave device.
o
The MODBUS slave device addresses, ‘Unit Identifier’, are assigned from 1
to 247 (decimal).
o
Address 0 is used as broadcast address.
• Host address- The IP address of destination (slave host address).
• Port- The Port number to be used when opening the connection. Usually the port
number remains unchanged and defaults to 502. In this case no call to this function is
necessary. However, if the port number must be different from 502, this function
must be called before opening the connection with openProtocol().