Modbus Rtu Slave Execution Error Codes - Siemens SIMATIC S7 System Manual

The Error output (Page 493) contains the result of executing the instruction. This output is
only valid if Done is ON. If Done is OFF, the error parameter is not changed.
Table 9- 12 Example program of S7-200 SMART CPU operating as a Modbus slave
LAD
9.3.3.4

Modbus RTU slave execution error codes

Error code
0
1
2
3
4
5
6
7
8
9
10
11
12
S7-200 SMART
System Manual, V2.3, 07/2017, A5E03822230-AF
Initialize the Modbus Slave protocol on
the first scan. Set the slave address to
1, set port 0 to 9600 baud with even
parity, all access to all I, Q and AI val-
ues, allow access to 1000 holding reg-
isters (2000 bytes) starting at VB0.
Execute the Modbus Slave protocol on
every scan.
Description
No error
Memory range error
Illegal baud rate or parity
Illegal slave address
Illegal value for Modbus parameter
Holding registers overlap Modbus Slave symbols
Receive parity error
Receive CRC error
Illegal function request/function not supported
Illegal memory address in request
Slave function not enabled
Invalid port number
Signal board port 1 missing or not configured
9.3 Modbus RTU library
STL
Network 1
LD SM0.1
CALL MBUS_INIT, 1, 1, 9600,
2, 0, 128, 32, 1000, &VB0,
M0.1, MB1
Network 2
LD SM0.0
CALL MBUS_SLAVE, M0.2, MB2
Libraries
493