Description
3401 Safety Instrumented System (SIS)
3401 Safety Instrumented System (SIS)
Module Clips Drive controller servo motor
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Definition of IO Link Protocol and Its Interface
IO Link is a peer-to-peer, serial digital communication protocol designed for periodic data exchange between sensors/actuators and controllers (PLCs). The IO Link protocol was first proposed by Siemens and has now become an international standard IEC 61131-9. With the advancement of Industry 4.0, the use of IO Link is becoming increasingly widespread. Today”s article will introduce the definition of the IO Link protocol and its interfaces.
Factory automation can be divided into execution layer, on-site layer, on-site control layer, workshop control layer, and management layer according to functional division. As shown in the following figure:
The execution layer includes various execution mechanisms (valves, pumps, motors, etc.) and sensors, which are the muscles and peripheral nerves of factory automation. They receive commands from the upper layer and complete specified actions.
The on-3401 Safety Instrumented System (SIS) site layer includes various distributed IO3401 Safety Instrumented System (SIS) systems, which are the central nervous system of factory automation. It conveys control instructions from the upper layer to the execution layer; And feedback the signals from the execution layer to the control layer, serving as the information center;
The on-site control layer includes various PLC systems, which are the brains of factory automation. It issues corresponding instructions and commands the execution layer to complete corresponding actions based on internal program requirements and signal feedback from the execution layer;
The workshop control layer (MES) and management layer communicate with various PLC systems at the management level to complete management tasks at the workshop and factory levels.
The IO Link protocol to be introduced in this article is a protocol that transfers data between the execution layer and the field layer. An IO Link system consists of the following components:
1) IO Link Master;
2) IO Link Device;
3) Non shielded 3-5 core standard cable;
4) Tools for configuring IO Link parameters;
The IO Link Master transfers data between the IO Link device and the PLC. It is usually a distributed IO module with IO Link connection channels on the module. The IO Link Device is connected to the channel of the IO Link Master through a cable, and the IO Link Master exchanges data with the PLC through a bus. As shown in the following figure:
Every IO Link device needs to be connected to a channel of the IO Link supervisor, so IO Link is a peer-to-peer communication protocol, not a bus protocol.
IO Link devices are divided into two types: sensors and actuators: sensors are usually the four pin interface of M12, and actuators are usually the five pin interface of M12.
According to IEC 60974-5-2, the definition of IO Link Device pins follows the following regulations:
1) Pin 1 (PIN1): 24V power supply positive pole;
2) Pin 3 (PIN3): 0V
3) Pin 4 (PIN4): IO Link communication or standard IO output;
The pin definition of the IO Link device is shown in the following figure:
Which types of equipment should PLC module manufacturers develop first?
We know that PLC, also known as programmable logic controller, collects variable data through various IOs to achieve the purpose of automated control. Therefore, developing PLC is largely about developing IO. However, with so many types of IO, which PLC module manufacturers should develop first? Let me share my opinion:
1. Digital input IO, including PNP and NPN digital input IO, counter input IO, etc.
2. Digital output IO, including PNP and NPN digital output IO, PWM pulse output IO, relay output IO, and so on.
3. Analog input IO, including current acquisition input IO, voltage acquisition input IO, temperature acquisition input IO, and so on. The current input IO can collect currents ranging from 0 to 20 milliamperes, while the voltage input IO can collect voltages ranging from negative 10V to positive 10V. Temperature acquisition IO includes thermocouples and thermal resistors.
4. The style of analog output IO is similar to that of analog input IO, but does not include temperature analog, mainly voltage and current type.
What are the characteristics of a demonstration system based on IO Link slave stations
IO Link is an industrial communication interface that is independent of any fieldbus and suitable for simple sensors and actuators at the lowest level of industrial control. The IO Link system includes IO Link devices (such as sensors and actuators), IO Link master stations, and cables for standard sensors. The system structure is shown in Figure 1. For example, when a remote IO module compatible with EtherNet/IP serves as the master station, in addition to standard I/O signals, the module sends and receives configuration data, diagnostic data, or enhanced process data through a pulse modulation process, which is then packaged into EtherNet/IP data packets and finally transmitted to the network master station, usually a PLC. In the above applications, the connection between remote I/O and IO Link devices remains the same as that of traditional discrete devices. The advantage of IO Link mainly lies in its greater information exchange capability, which was previously impossible to achieve with standard I/O devices. Another advantage of IO Link is that it does not rely on any fieldbus, and through any I/O module that complies with the IO Link protocol (including local I/O and remote I/O), IO Link sensors or actuators can be integrated into any fieldbus system.
In order to further study the architecture, communication mechanism, and development application of the IO Link system, an IO Link slave toolkit can be designed and developed, including a universal development module for IO Link, an IO Link analysis tool, and an IO Link slave protocol stack. The IO Link universal development module is the foundation for this work and also serves as a bridge between the IO Link master station and equipment signals. The IO Link analysis tool can help developers and testers analyze communication details to identify and solve problems. The IO Link slave protocol stack is a firmware library that provides a hardware abstraction layer and application program interface, allowing developers to easily and quickly develop IO Link slave products on various microprocessor platforms. The IO Link slave station studied in this article only focuses on digital (button) signal input and digital signal output (indicator light). The design of the IO Link universal development module only needs to be expanded on this basis to have the ability to process analog signals.
The IO Link Master module used in this article, USB IO Link Master, can connect IO Link devices to a PC, which can be configured and tested through the IO Link Device Tool software or demonstrated device functionality. IO Link devices must be described through a device description file (IODD file), which includes a set of XML text files and PNG graphic files, which contain information about device identification, communication characteristics, parameters, process data, and diagnostic data. The portion within the elliptical dashed line in Figure 2 is an IO Link three wire cable, with L+/I – being a 24 V DC power supply and C/Q being a signal line used to transmit process data, diagnostic data, configuration data, etc. The IO Link universal development module is mainly composed of data transceivers and microprocessors. It can process input signals from sensors and transmit information to the IO Link master station. It can also receive and process data information from the master station and transmit it to the actuator. The IO Link analysis tool can help developers view, record, analyze data, and understand communication details. This part of the design is not discussed in this article.
Introduction to IO Link Communication Mode3401 Safety Instrumented System (SIS)
IO Link devices can operate in SIO mode (standard I/O mode) or IO Link mode (communication mode). After power on, the device always operates in SIO mode. The port of the main station has different configuration methods. If configured in SIO mode, the main station considers the port as a standard digital input. If configured in communication mode, the main station will automatically identify the communicable devices for communication.
2.1 Data Types3401 Safety Instrumented System (SIS)
The three basic data types for IO Link communication are periodic data (or process data PD), non periodic data (or service data SD), and event.
The process data (PD) of the device is transmitted periodically in the form of a data frame, while service data (SD) is only exchanged after the master station issues a request. Figure 3 shows a typical IO Link message structure. When an event occurs, the “event flag” of the device is set, and the main station reads the reported event (service data cannot be exchanged during the reading process) upon detecting the setting. Therefore, events such as pollution, overheating, short circuits, or device status can be transmitted to the PLC or visualization software through the main station
2.2 Parameter data exchange
Since service data (SD) must be transmitted through PLC requests, SPDU (Service Protocol Data Unit) is defined. In the main station, requests for read and write services are written to SPDU and transmitted to devices through the IO Link interface.
The general structure of SPDU is shown in Figure 4, and its arrangement order is consistent with the transmission order. The elements in SPDU can take different forms depending on the type of service. SPDU allows access to data objects that are intended for transmission, while Index is used to specify the address of the requested data object on the remote IO Link device. In IO Link, there is a term called direct parameter page, which stores parameter information such as minimum cycle time, supplier ID, and master station commands. The data objects accessible in the direct parameter page can be selectively provided through SPDU.
HMT7742 is an IO Link slave transceiver chip that serves as a bridge between the MCU of external sensors or actuators and the 24V signal line that supports IO Link communication. When the IO Link device is connected to the master station, the master station initializes communication and exchanges data with the MCU. HMT7742 serves as the physical layer for communication.
Due to the fact that the three indicator lights (rated voltage 24 V) controlled by the output port of the MCU are powered by the IO Link power cord, it is necessary to monitor the current on the power cord in order to trigger appropriate corrective measures when the current exceeds a set threshold, such as removing the indicator lights from the IO Link power cord. The current monitoring module uses an INA194 current detection amplifier. As a high detection current detector, INA194 is directly connected to the power supply and can detect all downstream faults. It has a very high common mode rejection ratio, as well as a large bandwidth and response speed. It can amplify the voltage on the induction resistor 5O times and output it to the forward input terminal AIN0 of the MCU internal voltage comparator. When the voltage value of AIN0 exceeds the threshold set at the reverse input terminal, By controlling the low level output of PB0, the indicator LAMP can be cut off from the IO Link power line to achieve overcurrent protection function. This part of the circuit is shown in Figure 6.
Application of Data Acquisition IO Module in Thermal Power Plant System3401 Safety Instrumented System (SIS)
The Ethernet IO module is a data acquisition and control device. It uses Ethernet as a communication method to transmit data from various industrial control sensors and actuators to computers or other devices for management and monitoring. As a modern energy supply base, thermal power plants need to widely apply various intelligent control technologies to improve operational efficiency, reduce costs, and improve safety. In this context, the application of barium rhenium Ethernet IO modules is particularly important.
In the application of thermal power plants, the main function of the barium rhenium Ethernet IO module is to achieve real-time monitoring and control of the production process. By connecting to various sensors and actuators, the barium rhenium Ethernet IO module can collect real-time environmental parameters, machine operation status, and other data of the thermal power plant. By analyzing and processing these data, commanders can understand the operation of the thermal power plant and make corresponding adjustments. Compared to traditional automatic control systems, the barium rhenium Ethernet IO module has the advantages of stronger flexibility, faster reaction speed, and higher accuracy, which can greatly improve the operational efficiency and reliability of thermal power plants.
The real-time monitoring and control of thermal power plants require many capabilities of barium rhenium Ethernet IO modules. Here are several common application scenarios:
Firstly, the barium rhenium module can monitor parameters such as gas flow and water flow in thermal power plants. These parameters are crucial for ensuring the normal operation of the thermal power plant. Once these parameters undergo abnormal changes, the DO channel can be connected to the barium rhenium Ethernet IO module, and the alarm signal will immediately sound to remind the command personnel to handle it. Meanwhile, due to the fact that the barium rhenium Ethernet IO module can collect these data in real-time and transmit it to the monitoring system for recording, it can provide better technical support for quality management in thermal power plants.
Secondly, the barium rhenium Ethernet IO module can also monitor the operating status of mechanical equipment in thermal power plants. This includes parameters such as temperature, pressure, vibration, etc. By monitoring and analyzing these parameters, the barium rhenium Ethernet IO module can detect machine equipment faults in a timely manner, thereby avoiding the expansion of losses. In addition, during machine equipment maintenance, historical data recorded by the barium rhenium Ethernet IO module can be used to develop more scientific and reasonable maintenance plans, reduce maintenance costs, and improve maintenance efficiency.
Finally, the barium rhenium Ethernet IO module can also help thermal power plants achieve distributed control. We can remotely control and monitor multiple areas of the thermal power plant by connecting multiple barium rhenium modules to a network. This not only reduces the on-site debugging of equipment, but also strengthens the evaluation of equipment reliability.
In summary, the barium rhenium Ethernet IO module has unique advantages in real-time monitoring and control of thermal power plants. It can help command personnel monitor machine data in real-time, discover abnormal information, take timely measures to avoid impacts, and improve production efficiency and safety.
Remote IO modules based on Ethernet communication are widely used in the field of industrial IoT
With the development of IIOT (Industrial IOT) industrial Internet of Things technology, many traditional assets need to be connected to the internet to achieve unified data collection, analysis, processing, and storage, breaking the traditional phenomenon of device information silos. Therefore, the MQTT Ethernet IO acquisition module M160T, which supports the Internet of Things protocol, is able to unleash its potential by being compatible with existing devices and able to connect to IoT platforms. The MQTT Ethernet IO acquisition module will be widely used in industrial IoT, such as smart property, smart parks, smart factories, smart transportation, smart water conservancy, smart agriculture, smart campuses, smart communities, smart distribution, smart water conservancy, and many other industries.
Ethernet communication technology is a mature communication technology that has been widely applied. Therefore, Ethernet communication is the first choice for enterprises to connect various assets to the Internet of Things platform. Its reasons are stable and reliable, mature technology, fast transmission speed, and fast construction wiring.3401 Safety Instrumented System (SIS)
For traditional various assets, such as low-voltage distribution rooms, air compressor rooms, property and living pump rooms, street light control, liquid level collection, temperature and humidity collection, etc., through the MQTT Ethernet IO collection module, they can be quickly connected to the Internet of Things platform.
So, what characteristics do MQTT Ethernet IO modules need to have when used in IoT solutions? The details are as follows:
1. Actively connect to cloud platforms:
Based on the characteristics of Ethernet communication networking, the Ethernet IO acquisition module must support the TCP Client function, which is not only the TCP client function, so that the Ethernet IO module can actively connect to the IoT platform without the need for complex settings such as peanut shells;
2. Compatible with existing systems:
Support TCP Server and Modbus TCP protocol functions, which can be compatible with traditional upper computer systems or device access of HMI”s TCP client;
3. Access to IoT platforms:
Supports standard MQTT protocol and Modbus TCP protocol, and can be connected to various MQTT protocol IoT platforms such as Huawei Cloud and Alibaba Cloud, or traditional SCADA and DCS systems;
4. Rich IO interfaces and scalability:
There are various types of data to be collected on site, and it is necessary to support the collection of various devices such as 4-20Ma, RS485, DI, DO, etc. At the same time, it is also necessary to have the ability to read RS485 device instrument data or expand the functions of the IO acquisition module;
5. Easy installation method:
The volume of the control box is very limited, so it is necessary to use directly inserted and unplugged wiring terminals, as well as a rail installation method.
6. Industrial grade design
The industrial environment is harsh, and the Ethernet IO module must adopt an industrial grade design to ensure continuous and stable operation in harsh environments.
Through the MQTT Ethernet IO acquisition module, there is no need to replace various existing enterprise assets and the digital transformation of accessing IoT platforms can be quickly achieved. Therefore, the MQTT Ethernet IO acquisition module will be widely used in industrial IoT, such as smart properties, smart parks, smart factories, smart transportation, smart water conservancy, smart agriculture, smart campuses, smart communities, smart power distribution, smart water conservancy, and many other industries.
1.Has been engaged in industrial control industry for a long time, with a large number of inventories.
2.Industry leading, price advantage, quality assurance
3.Diversified models and products, and all kinds of rare and discontinued products
4.15 days free replacement for quality problems
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