ModbusView TCP is an easy to use program that monitors and simulates Modbus ASCII, RTU and TCP/IP communications on your PC. It enables your PC to act as both a Modbus master and a slave device making it easy for you to simulate the action of your HMI machine, instruments, PLCs etc. ModbusView TCP can be downloaded below and will operate in a 15-minute trial mode. Once purchased, you will be emailed with a serial number to enable unlimited use.
Download a copy of the unregistered program from this site. The unregistered version of ModbusView TCP has all the features of the registered version except there is a time limit of 15 minutes. After 15 minutes you have to restart the program. This will allow you to trial the program before buying.
Modbus is an industrial control protocol run over serial or Ethernet networks. Many PLCs, panel meters, PID controllers, HMIs, IO modules and pieces of industrial equipment can speak Modbus. ModbusView TCP allows you to interrogate and control these devices from your computer.
The Modbus master establishes a connection with the slave. The slave waits for an incoming command from the master and responds appropriately. ModbusView TCP can act as either a Modbus master or slave.
The slave can have 4 different types of internal variables that can be accessed by the master.
- Coils which are digital bits that can be read and written to. They are numbered from 00001 to 09999
- Input Status which are digital bits that can be read. They are numbered from 10001 to 19999
- Input Registers which are 16 bit integers that can be read. They are numbered from 30001 to 39999
- Holding Registers which are 16 bit integers that can be read and written to. They are numbered from 40001 to 49999
Each type in the Modbus specification can have up to 9,999 variables. The protocol can be extended to represent up to 65,536 variables using full 16 bit addressing. ModbusView TCP allows both specification-compliant and full 16 bit addressing.
The Modbus protocol has a number of different functions, some of which are specific to certain Modicon controllers and some of which are rarely used. ModbusView TCP sends and responds to a wide range of the most common Modbus commands including:
- Function 1: Read Coil Status
- Function 2: Read Input Status
- Function 3: Read Input Registers
- Function 4: Read Holding Registers
- Function 5: Write to a Coil
- Function 6: Write to a Holding Registers
- Function 15: Write to Multiple Coils
- Function 16: Write to Multiple Holding Registers
For a more detailed explanation of the Modbus protocol family visit the Web Site www.modbus.org.