• Modbus Framework
• Modbus Software Download

Hi Roberto,The PLC will connect with PC directly, in my application, there will not use any other ways to embedded the protocol, just need to use RS-232 to communicate with it. The PLC provider just states that the communication protocol complys with Modbus RTU. I will use the PLC to turn on or off a light. I have read a protocol doc.

Modbus Framework

May 25, 2014 - Degree Programme in Information Technology. Trung-Hieu Nguyen. Title of Thesis. Serial communication and MODBUS protocol implementation using. Jump to Programming the CUWIN - Add a reference to the Modbus.dll file in netcf folder introduced above. Add a using declaration to the source file that.

Modbus.org, it said that modbus can read out a coil's status, and also can read out the register's value, I'm confused because I do not know the distinguish between coil and the register. Please give a hint, your advise is highly appreciated. Hi David, basically modbus permits you to read and write into the PLC memory: it's up to the program resident inside the PLC to determine the content of the memory to read and what to do with the memory written to by the computer.In order to establish a serial communication with the PLC your program must:1.

Open the serial port with proper parameters the plc can use to communicate2. Prepare the memory arrays to calculate the CRC3. Prepare a message with the correct PLC address, function number (0x03: read if I'm not in remembering), addressof memory to read and width of memory read, CRC4. Send to the PLC which should receive, check the message and respond with an appropriate ACK message5. Wait for the response and check it (calculate the CRC on the answer and check with the CRC received by the PLC)6.

Modbus Software Download

If it's ok, read the responseWhat I exactly don't know is which part of the protocol is automatically performed by the PLC and which one is to be written by you inside that device. Shortly I will attach some source code I developed to communicate.