105BCommunication processor
12.5 Modbus communication
S7-1200 Programmable controller
594
System Manual, 11/2011, A5E02486680-05
For example, after MB_SERVER is placed in a LAD network, you can go to a previous
network and assign the HR_Start_Offset value. The value must be assigned prior to
execution of MB_SERVER.
Entering a Modbus server
variable using the default DB name:
1.
Set the cursor in the parameter field and
type an m character.
2.
Select "MB_SERVER_DB" from the drop-
list of DB names.
3.
Select
"MB_SERVER_DB.HR_Start_Offset" from
the drop-list of DB variables.
Table 12- 62 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
connect 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 a optimized MB_HOLD_REG area (must be a standard 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).