Mb_Master - Siemens SIMATIC S7 System Manual
Hide thumbs
Also See for SIMATIC S7:
- System manual (866 pages) ,
- Functional safety manual (212 pages) ,
- User manual (134 pages)
Table of Contents
Advertisement
12.5.3.2
MB_MASTER
Table 12- 67 MB_MASTER instruction
LAD / FBD
Table 12- 68 Data types for the parameters
Parameter and type
REQ
IN
MB_ADDR
IN
MODE
IN
DATA_ADDR
IN
DATA_LEN
IN
DATA_PTR
IN
DONE
OUT
BUSY
OUT
ERROR
OUT
STATUS
OUT
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
SCL
"MB_MASTER_DB"(
REQ:=_bool_in_,
MB_ADDR:=_uint_in_,
MODE:=_usint_in_,
DATA_ADDR:=_udint_in_,
DATA_LEN:=_uint_in_,
DONE=>_bool_out_,
BUSY=>_bool_out_,
ERROR=>_bool_out_,
STATUS=>_word_out_,
DATA_PTR:=_variant_inout_);
Data type
Description
Bool
0=No request
1= Request to transmit data to Modbus slave
V1.0: USInt
Modbus RTU station address:
V2.0: UInt
Standard addressing range (1 to 247)
Extended addressing range (1 to 65535)
The value of 0 is reserved for broadcasting a message to all Modbus
slaves. Modbus function codes 05, 06, 15 and 16 are the only function
codes supported for broadcast.
USInt
Mode Selection: Specifies the type of request (read, write, or diagnostic).
See the Modbus functions table below for details.
UDInt
Starting Address in the slave: Specifies the starting address of the data to
be accessed in the Modbus slave. See the Modbus functions table below
for valid addresses.
UInt
Data Length: Specifies the number of bits or words to be accessed in this
request. See the Modbus functions table below for valid lengths.
Variant
Data Pointer: Points to the M or DB address (Standard DB type) for the
data being written or read.
Bool
The DONE bit is TRUE for one scan, after the last request was completed
with no error.
Bool
Bool
The ERROR bit is TRUE for one scan, after the last request was
terminated with an error. The error code value at the STATUS parameter
is valid only during the single scan where ERROR = TRUE.
Word
Execution condition code
Description
The MB_MASTER instruction communicates as a
Modbus master using a port that was configured by
a previous execution of the MB_COMM_LOAD
instruction. An instance data block is assigned
automatically when you place the MB_MASTER
instruction in your program. This MB_MASTER
instance data block is used when you specify the
MB_DB parameter for the MB_COMM_LOAD
instruction.
0 – No MB_MASTER operation in progress
1 – MB_MASTER operation in progress
105BCommunication processor
12.5 Modbus communication
603
- Quick Links:
- Introducing the S7-1200 Plc
Hide quick links:
Advertisement
Table of Contents
