Siemens SIMATIC S7 System Manual page 191
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Modbus address parameter
DATA_ADDR
Mode 0
Read
00001 to 09999
10001 – 19999
30001 - 39999
40001 to 49999
400001 to 465536(Extended)
Mode 1
Write
00001 to 09999
40001 to 49999
400001 to 465536(Extended)
00001 to 09999
40001 to 49999
400001 to 465536(Extended)
Mode 2
Some Modbus slaves do not support single bit or word writes with Modbus functions 05H and 06H. In these cases, Mode 2
is used to force single bit and word writes using Modbus functions 15H and 16H.
Write
00001 to 09999
40001 to 49999
400001 to 465536(Extended
Mode 11
Reads an event counter word from the Modbus slave that is referenced as an input to MB_ADDR
On a Siemens S7-1200 Modbus slave, this counter is incremented every time that the slave receives a valid read or
write (non-broadcast) request from a Modbus master.
The returned value is stored in the word location specified as the input to DATA_PTR.
A valid DATA_LEN is not required for this mode.
Mode 80
Checks the communication status of the Modbus slave that is referenced as an input to MB_ADDR
The setting of the NDR output bit on the MB_MASTER instruction indicates that the addressed Modbus slave
responded with the appropriate response data.
No data is returned to your program.
A valid DATA_LEN is not required for this mode.
Mode 81
Resets the event counter (as returned by Mode 11) on the Modbus slave that is referenced as an input to MB_ADDR
The setting of the NDR output bit on the MB_MASTER instruction indicates that the addressed Modbus slave
responded with the appropriate response data.
No data is returned to your program.
A valid DATA_LEN is not required for this mode.
S7-1200 Programmable controller
System Manual, 11/2009, A5E02486680-02
MB_MASTER Modbus functions
Address type
Output bits
Input bits
Input registers
Holding registers
Output bits
Holding registers
Output bits
Holding registers
Output bits
Holding registers
Programming instructions
6.3 Global library instructions
Modbus data length
parameter DATA_LEN
1 to 2000
1 to 2000
1 to 125
1 to 125
1 (single bit)
1 (single word)
2 to 1968
2 to 123
1 to 1968
1 to 123
Modbus function
01H
02H
04H
03H
05H
06H
15H
16H
15H
16H
191
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- Introducing the S7-1200 Plc
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