Modbus Communications - Datakom D-500 MK2 User Manual

D-500 MK2 User Manual

35. MODBUS COMMUNICATIONS

This chapter is a brief description of the Modbus properties of
the controller. For a complete documentation please use "500
Modbus Application Manual"
The unit offers the possibility of MODBUS communication through below carriers:
-RS485 serial port, with adjustable baud rate between 2400 and 115200 bauds
-MODBUS-TCP/IP through Ethernet port (100Mb)
-MODBUS-TCP/IP through GPRS (85/42kb), client mode through Rainbow Scada only
The MODBUS properties of the unit are:
-Data transfer mode: RTU
-Serial data: selectable baud rate, 8 bit data, no parity, 1 bit stop
-Modbus-TCP/IP: Ethernet 100Mb or GPRS Class 10.
-Supported functions:
-Function 3 (Read multiple registers)
-Function 6 (Write single register)
-Function 16 (Write multiple registers)
Each register consists of 2 bytes (16 bits). A larger data structure will contain multiple registers.
The Modbus communications requires a slave address to be assigned to each device in the Modbus
network. This address ranges between 1 and 240 and allows the addressing of different slave devices in
the same network.
Each device in the same RS-485 serial network must be
assigned a different slave address. Otherwise the Modbus
communications will not be performed.
Devices using Modbus-TCP/IP with different IP or port
addresses may use any slave address. It is advised to set
these slave addresses to the default setting which is 1.
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Firmware V-6.3