7
vacon • 76 Modbus TCP / Modbus UDP
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7.3 Data addresses in Modbus messages
All data addresses in Modbus messages are referenced to zero. The first occurrence of a data item
is addressed as item number zero. For example:
• The coil known as 'Coil 1' in a programmable controller is addressed as 'Coil 0000' in the
data address field of a Modbus message.
• Coil 127 decimal is addressed as 'Coil 007E hex' (126 decimal).
• Holding register 40001 is addressed as register 0000 in the data address field of the mes-
sage. The function code field already specifies a 'holding register' operation. Therefore the
'4XXXX' reference is implicit.
• Holding register 40108 is addressed as register 006B hex (107 decimal).
7.3.1 Modbus memory map
The VACON
®
variables and fault codes as well as the parameters can be read and written from
Modbus. The parameter addresses are determined in the application. Every parameter and actual
value has been given an ID number in the application. The ID numbering of the parameters as well
as the parameter ranges and steps can be found in the application manual in question. The
parameter values are given without decimals. If several parameters/actual values are read with one
message, the addresses of the parameters/actual values must be consecutive.
Table 25. Supported functions
NOTE! Broadcasting is not supported in TCP.
7.3.2 Modbus data mapping
7.3.2.1 Coil registers
Coil registers contain binary data (Read/Write). See Table 26.
Table 26. Defined coil registers
Function code Current terminology Access type Address range (hex)
1 (0x01) Read coils Discrete 00000-0FFFF
2 (0x02) Read Input Discrete Discrete 10000-1FFFF
3 (0x03) Read holding registers 16bit 40000-4FFFF
4 (0x04) Read input registers 16bit 30000-3FFFF
5 (0x05) Force single coils Discrete 00000-0FFFF
6 (0x06) Write single register 16bit 40000-4FFFF
15 (0x0F) Force multiple coils Discrete 00001-0FFFF
16 (0x10) Write multiple registers 16bit 40000-4FFFF
23 (0x17) Read/Write multiple registers 16bit 40000-4FFFF
Address Function Purpose
0001 RUN/STOP Control Word, bit 0
0002 Direction Control Word, bit 1
0003 Fault reset Control Word, bit 2
0017 Reset Clears operation days trip counter
0018 Reset Clears energy trip counter
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