Description
In addition to the software required STEP 7> = V13 SP1 (TIA Portal) , you also need S7-1200 CPU firmware version> = V4 (Article ID: 6ES721x-1xx40-0XB0).
Modbus RTU communication through the following modules.
- CB 1241 RS485 (order number: 6ES7241-1CH30-1XB0) binding S7-1200 CPU firmware to> = V4.1.1.
- CM 1241 RS422 / 485 (order number: 6ES7241-1CH32-0XB0) binding to the communication module firmware upgrade> = V2.1
- CM 1241 RS232 (order number: 6ES7241-1AH32-0XB0) combined with the communication module firmware upgrade to> = V2.1
In addition to "Modbus_Master" instruction, but also "Modbus_Comm_Load" command to establish communications.
Are two blocks 7 (TIA Portal) in STEP, "Instructions> Communication> Communication processor> MODBUS (RTU)> = Version 3.0".
Fig. 01
Modbus_Comm_Load
Modbus_Comm_Load block is used to select the communication module is provided with communication parameters and parameter master (or slave) of the connection parameters.
Fig. 02
Before the first call Modbus_Master (or Modbus_Slave), non-cyclic blocks run once and must Modbus_Comm_Load run is completed (DONE = 1). Modbus_Comm_Load be in the first cycle of the program call (by enabling the system memory bit M1.0 in the hardware configuration). After inserting the communication module in the hardware configuration, you can sign in name PORT parameter transmission communication module.
BAUD communication parameters (baud rate) and the PARITY (parity) must match the slave address. In the data structure MB_DB transmission parameters MB_DB Modbus_Master (or Modbus_Slave) background data, thus defining the communication module (identified by the parameter PORT) of MODBUS master (or slave). In addition, examples of the data must be changed in Modbus_Comm_Load static parameters for duplex mode of operation, the initial value setting (0 = full duplex (RS232) , 1 = full duplex (RS422) four-wire mode, 4 = half duplex (RS485) two-wire mode).
Fig. 03
Modbus_Master
using function blocks defined Modbus_Master communication module, and configured to select a block Modbus_Comm_Load MODBUS master.
Fig. 04
Modbus_Master block used to select the need to communicate with MODBUS slave match, the specified function code definition storage area and local data. The following table describes the parameters.
| Parameter | Description |
|---|---|
| REQ | Enable communication. |
| MB_ADDR | MODBUS-RTU station address. |
| MODE | Type of the request: "0" = read, "1" = write "104" = read slave input word (address register 65535) ... |
| DATA_ADDR | MODBUS defined start address (offset + = Slave Address Register): the MODE = 104: 0 = offest |
| DATA_LEN | MODBUS define the data length (in the form of bits or bytes): the MODE = 104: Words |
| DATA_PTR | Defining the master receiving area and local data transmission region. DATA_PTR parameter must reference a data block, the "Optimized block access" attribute data block must have been disabled. |
Table 01
"MODBUS (RTU)" instruction library also contains functions "MODBUS" instructions library.
However, if Modbus_Slave block, the MB_HOLD_REG parameter only supports the "Word" data type of one-dimensional array.
Download
Download include "109474481_S7-1200_Modbus_Master_V13-SP1.zip" project. It contains the following program folder.
- "CPU-V4_CM1241RS485-V2d1" use S7-1200 CPU firmware version V4.0 of Modbus-RTU communication, and by CM 1241 RS422 / 485 V2 firmware version.
- "CPU-V4d1_CB1241RS485" use S7-1200 CPU firmware V4.1.1 version of the Modbus-RTU communication via CB 1241 RS485.
Address of the slave Modbus 1, from a predetermined start address 53248 (16 # D000) 9 may read the input word (such ebm-papst's Motor VarioDrive C) through the RS485 communication using the monitoring table.
Copy "109474481_S7-1200_Modbus_Master_V13-SP1.zip" file into a separate directory and then double-click the file to open spot. You can use STEP 7 to open and process the project data extraction.
S7-1200_Modbus_Master_V13-SP1.zip (3,9 MB)