Click the blue text to follow! PLC Old Li Talks Technology: What’s So Difficult About PLCs? Discussing Those Pitfalls from a Practical Perspective Last week, Xiao Zhang rushed over to me, saying: “Old Li, the production line 3 has stopped again, the system is alarming, and I’ve been looking at it for a long time … Read more
Recently, a young electrician came to ask about PLC configuration. Looking at his program, I was truly speechless. Today’s young people seem to just throw everything into the code without considering the basic scanning cycle. Back in the day when I started in this field, we didn’t even have decent programming software; we used old-fashioned … Read more
Supported baud rate range: 9600—-12M Order number: 6ES7-277-0AA22-0XA0 1. First, install the GSD file for EM277 (GSD file download link: http://www.con-star.com/download/download11.html) 2. In the path PROFIBUS DP—Additional Field Devices—PLC—SIMATIC—EM277, drag it into the DP line configuration 3. Click on “EM277 profibus dp” to see various types of communication data classifications, such as “2 BYTE OUT/ … Read more
Modbus Communication Programming Example (1) Recently, I have been writing about Modbus and fieldbus introductions separately, which are more conceptual and do not involve specific examples. Many readers may still find it insufficiently detailed. Since I am no longer engaged in specific programming debugging, providing direct examples is quite challenging. I referenced some materials from … Read more
Recently, I’ve encountered several newcomers asking about the PLC scan cycle issues, it’s really frustrating! They keep making the same mistakes over and over again. After working in this field for over ten years, I’ve seen too many program crashes caused by a lack of understanding of the scan cycle principles. To put it bluntly, … Read more
Introduction: The “Dimensionality Reduction” of Communication Methods Suppose you want to convey a message to a friend: Writing a Letter (HTTP) Clearly write the address, affix a stamp, and wait for the mailman to deliver it. The recipient opens the letter to read it. Making a Phone Call (RPC) Dial directly, and once connected, have … Read more
Click 👆 aboveFollowEngineer Yan Ji and ★ Star Mark ★. Modbus-RTU Protocol The RTU ADU is shown in the figure below. In addition to the core PDU, this ADU contains only two pieces of information. First, the address is used to define the slave device corresponding to the PDU. In most networks, address 0 is … Read more
Through previous studies, we learned that BLE devices act as servers, storing some data, while clients achieve corresponding functions by reading, writing, and configuring this data. Previously, we learned about broadcasting and connections; today, let’s take a look at what happens after a connection is established.Discovery of Services and CharacteristicsAfter a device establishes a connection, … Read more
For more exciting content, click to follow “PLC Enthusiasts” The Siemens S7-1200 can communicate via Modbus RTU through communication modules, with the PLC serving as the controller, typically acting as the Modbus master. When functioning as a Modbus master, it generally polls parameters from multiple slave devices. This article introduces the timed polling program for … Read more
Click 👆 above to follow Engineer Yan Ji and ★star★. Protocol Definition 1. Modbus is a request-response protocol implemented using a master-slave relationship. 2. The Modbus protocol introduces different application data units to change the packet format used in serial communication or to allow the use of TCP/IP and User Datagram Protocol (UDP) networks. Its … Read more