Siemens Simatic S7 Series

Libraries
9.3 Modbus library instructions
S7-200 SMART
448 System Manual, 09/2015, A5E03822230-AC
9.3.3.4
Modbus slave execution error codes
Table 9- 32
Error codes
Description
0
No error
1
Memory range error
2
Illegal baud rate or parity
3 Illegal slave address
4
Illegal value for Modbus parameter
5
Holding registers overlap Modbus Slave symbols
6
Receive parity error
7
Receive CRC error
8
Illegal function request/function not supported
9
Illegal memory address in request
10
Slave function not enabled
11
Invalid port number
12
Signal board port 1 missing or not configured
9.3.4
Modbus master example program
This example program shows how to use the Modbus Master instructions to write and read
four holding registers to and from a Modbus slave each time input I0.0 is turned on.
The CPU writes four words starting at VW100 to the Modbus slave. The data is written to
four holding registers in the slave starting at address 40001.
The CPU then reads four holding registers from the Modbus slave. The data comes from
holding registers 40010 - 40013 and is placed into the V memory of the CPU starting at
VW200.
Figure 9-1 Example Program Data Transfers