Siemens SIMATIC S7-1200 - Page 1263

Communication processor and Modbus TCP
13.8 Legacy Modbus TCP communication
S7-1200 Programmable controller
System Manual, V4.2, 09/2016, A5E02486680-AK
1263
Table 13- 142 MB_SERVER execution condition codes
1
STATUS
(W#16#)
Response code to
Modbus server
(B#16#)
Modbus protocol errors
7001 MB_SERVER is waiting for a Modbus client to connect to the assigned TCP port. This
code is reported on the first execution of a connect or disconnect operation.
7002 MB_SERVER is waiting for a Modbus client to connect to the assigned TCP port. This
code is reported for any subsequent executions, while waiting for completion of a con-
nect or disconnect operation.
7003
A disconnect operation has successfully completed (Only valid for one PLC scan).
8187
Invalid pointer to MB_HOLD_REG: area is too small
818C Pointer to an optimized MB_HOLD_REG area (must be a non-optimized DB area or M
memory area) or Blocked process timeout exceeds the limit of 55 seconds. (S7-1200
specific)
8381
01
Function code not supported
8382
03
Data length error
8383
02
Data address error or access outside the bounds of the MB_HOLD_REG address area
8384
03
Data value error
8385
03
Data diagnostic code value not supported (function code 08)
1
In addition to the MB_SERVER errors listed above, errors can be returned from the
underlying T block communication instructions (TCON, TDISCON, TSEND, and TRCV
(Page 857)).