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MODBUS Communication

Communication using the MODBUS interface

Instrument Control Toolbox™ supports the MODBUS interface over TCP/IP or Serial RTU. You can use it to communicate with MODBUS servers, such as controlling a PLC, communicating with a temperature controller, controlling a stepper motor, sending data to a DSP, reading bulk memory from a PAC controller, or monitoring temperature and humidly on a MODBUS probe.

Create the interface object using the modbus function, and use the read, write, writeRead, and maskWrite functions for communication.

For an example that shows the entire workflow of reading a register from a PLC, see Read Temperature from a Remote Temperature Sensor.

Functions

modbusCreate MODBUS object
readRead data from a MODBUS server
writePerform a write operation to the connected MODBUS server
writeReadPerform a write then read operation on groups of holding registers in a single MODBUS transaction
maskWritePerform mask write operation on a holding register
instrhwinfoInformation about available hardware
clearRemove instrument objects from MATLAB workspace

Topics

MODBUS Interface Supported Features

Instrument Control Toolbox MODBUS support lets you communicate with MODBUS servers and applications over TCP/IP or Serial RTU.

Create a MODBUS Connection

To communicate over the MODBUS interface, you first create a MODBUS object using the modbus function. Creating the object also makes the connection.

Configure Properties for MODBUS Communication

You can use properties to set up the MODBUS communication during object creation or any time.

Read Data from a MODBUS Server

You can read data from the MODBUS server connected to the modbus object. You can read coils, inputs, input registers, and holding registers.

Read Temperature from a Remote Temperature Sensor

This example shows how to read temperature and humidity measurements from a remote sensor on a PLC connected via TCP/IP.

Write Data to a MODBUS Server

You can write data to the MODBUS server connected to the modbus object. You can write to coils and holding registers.

Write and Read Multiple Holding Registers

You can perform a combination of one write operation and one read operation on groups of holding registers in a single MODBUS transaction.

Modify the Contents of a Holding Register Using a Mask Write

You can modify the contents of a holding register using a combination of an AND mask, an OR mask, and the register's current contents.

Troubleshooting

Troubleshooting MODBUS Interface

Try these tips if you have problems using the toolbox with the MODBUS interface. Includes information about MODBUS supported platforms, configuration and connection, and other interface-specific tips.

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