ProSoft Technology 5202-DFNT-MCM4 - Manual (Page 31)

MCM Protocol Configuration MCM ♦ ProLinx Gateway
Driver Manual Modbus Master/Slave
ProSoft Technology, Inc.
Page 31 of 80
October 16, 2009
3.2.8 MB Address in Device
This parameter specifies the starting Modbus register or bit address in the slave
to be used by the command. Refer to the documentation of each Modbus slave
device for the register and bit address assignments valid for that device.
The Modbus Function Code determines whether the address will be a register- or
bit- level OFFSET address into a given data type range. The offset will be the
target data address in the slave minus the base address for that data type. Base
addresses for the different data types are:
ƒ 00001 or 000001 (0x0001) for bit-level Coil data (Function Codes 1, 5, and
15).
ƒ 10001 or 100001 (1x0001) for bit-level Input Status data (Function Code 2)
ƒ 30001 or 300001 (3x0001) for Input Register data (Function Code 4)
ƒ 40001 or 400001 (4x0001) for Holding Register data (Function Codes 3, 6,
and 16).
Address calculation examples:
ƒ For bit-level Coil commands (FC 1, 5, or 15) to read or write a Coil 0X
address 00001, specify a value of 0 (00001 - 00001 = 0).
ƒ For Coil address 00115, specify 114
(00115 - 00001 = 114)
ƒ For register read or write commands (FC 3, 6, or 16) 4X range, for 40001,
specify a value of 0
(40001 - 40001 = 0).
ƒ For 01101, 11101, 31101 or 41101, specify a value of 1100.
(01101 - 00001 = 1100)
(11101 -10001 = 1100)
(31101 - 30001 = 1100)
(41101 - 40001 = 1100)
Note: If the documentation for a particular Modbus slave device lists data addresses in
hexadecimal (base16) notation, you will need to convert the hexadecimal value to a decimal value
to enter in this parameter. In such cases, it is not usually necessary to subtract 1 from the
converted decimal number, as this addressing scheme typically uses the exact offset address
expressed as a hexadecimal number.