What is the essence of automation? The fact that the entire flow of information is transmitted from primary sources (sensors). It is assumed that the incoming data must correspond to reality, present information in real time, which implies a high update rate. Only in this way it will be possible to effectively monitor the control object in order to prevent false alarms and emergency situations. Analog and digital I / O modules can help with this.
Content
To connect a remote access device, which is used to accumulate a huge amount of data, a number of auxiliary mechanisms (executive) are used. How does the unit work? It measures the received analog and discrete indicators, which convert the data to the controller, as well as the control device, server (cloud), PC and other types of equipment.
Key characteristics of I / O nodes:
Input-output nodes are:
Kinds | Description |
---|---|
Discrete | The following functionality is provided: reception and transformation of received commands, including discrete ones, which are then sent to the general grid. It is done by using one of the included protocols, which is connected immediately after the receipt of the corresponding command. |
Analog | It collects and further processes the received information of an analog type. After that, it is broadcast to the main server, which decrypts according to the current protocol. |
It is worth paying attention to the fact that in each of the cases under consideration, the received command will be indicated within one of the ranges:
Under certain circumstances, it is necessary to equip specialized ports that will help to receive a signal from an RTD or thermocouple.
Discrete-type modules assume the presence of a logical command in a certain range, while analogue modules agree with their electromagnetic performance, comparable to the actuators that are controlled by the system.The input nodes receive signals from the common bus through a certain protocol, after which they are transmitted to the output lines.
It should be noted that both all channels of the modules and the supply circuits have galvanic isolation from the common bus.
The units used can work with one of the many communication protocols: Modbus, DeviceNet, RTU. The principle of the exchange of information protocols between the node and the controller is as follows: master and slave, where the module is the slave. The processor of the device, after requesting data from all channels and fixing their state, waits for an initiating command from the PLC to receive and transmit this information.
There are popular models where the exchange command initiates the input node itself, which received information about the channel state change. There is an address transfer of data from the node to the PLC. The processor is also able to perform additional functions, such as:
The best manufacturers produce models in several modifications. They differ in functionality, average price, capabilities, technical characteristics, material of manufacturing of component parts, interaction with the PLC via a common bus. Let's dwell on each option in more detail.
Data exchange takes place using the DeviceNet protocol. A universal model that allows you to use different communication procedures, including change (COS). There is a multibyte signal input. What it is? First of all, the optimal solution for remote I / O for ACS. The series includes standard modules and specimens with special connectors to be able to connect sensors.
There are eight channels of input-output of discrete signals with an open PNP- or NPN-collector. The channels are optically isolated from the data source or load. There is also protection against overcurrent, when the polarity of the supply voltage is reversed, from too high a voltage.
All equipments support DeviceNet protocol. It is possible to connect three additional expansion nodes to the main module. Additional devices are able to work on DeviceNet / ModBus networks. This product makes it possible:
At the same time, the speed of information transfer directly depends on the distance between the node and the host device. As a result, we get the following picture:
The weight of the modules, depending on the brand, ranges from 64 to 59 grams. There are such additional features:
The presence of a special e-Con connector in the assembly for connecting sensors makes the connection quick and hassle-free, while saving free space during installation.
An overview of the technical characteristics will show the following picture:
For data exchange, the Modbus RTU protocol is used, and it is possible to perform only one procedure: to carry out a cyclic poll (POLL) and 1-byte information input. The model allows you to expand the number of ports for output and input signals of PLCs, operator panels or PC.
The number of channels is 8, which are optically isolated from the load and from the signal source, as well as from voltage surges, polarity reversals, and so on. There is an automatic setting of the baud rate, which corresponds to the speed of the host equipment (PC, PLC, etc.). The maximum number of connections of such basic modules to the master is 63. Additional expansion nodes can be connected to operate in the DeviceNet / ModBus network.
A very compact product with a width of 26 mm. For DIN rail or panel mounting with bolts. Connecting sensors is quick and easy using the e-Con connectors. Able to work at a considerable distance - up to 800 m. In terms of their parameters, they are practically similar to the previous version.
A compact device that includes:
Can simultaneously combine 64 I / O devices and use them for control. The equipment is equipped with plug-in terminals that allow you to quickly connect external elements. Installation of the structure is carried out on a DIN rail. The ability to disconnect the terminal block and the control unit makes it possible to carry out maintenance of the system without turning off the communication channel and the power source. The structure can be installed with insufficient free space, since its small dimensions allow it to be done without much effort and ingenuity.
The products are used in the following areas:
To determine the best product, it is necessary to study the rating of quality models, determine the selection criteria, clarify their advantages and disadvantages, as well as the average price, and understand their features. The advantages of the ARIO module include:
The scope of application of devices of this type, provided that we are talking about designs providing for the use of such devices, are as follows:
When it becomes necessary to purchase modules, a lot of questions arise, including which company is better to choose a product. There are many popular models, manufacturers try to please the most meticulous users. Smart options cost a lot of money, branded options are not inexpensive.
Which brand is better to buy depends on the user's preferences and the scope of the device. Customer reviews, which are worth paying attention to, are also important. It is better not to make mistakes when choosing, since the end result may be negative and the money will be wasted.
Before visiting specialized outlets or ordering a design online in an online store, it is worth listening to the recommendations of specialists in this field and getting practical advice from them. It is necessary not to miss new items of both Russian and foreign production. According to buyers, you can choose a quality product at a budget price. It is not possible to make such a device with your own hands, and there is no need for this. But you can install it without assistance.
The four-channel module is based on the DAC 8775, has an integrated LM 5166 converter, which makes it possible to bring the power dissipation to an indicator of 1 W. The device requires an input voltage of 1.5 to 40 V. It is able to regenerate 4 separate sources at the input, used to control the connection of peripherals. Its features include the presence of adaptive power management of the current outputs, as well as an indicator of the switched current of 4-20 mA per channel.
How much does the product cost? The manufacturer offers his product at a negotiated price, depending on the configuration.
The products are categorized as fully featured, complete analog input modules that meet today's demands for efficiency and functionality, and channel density, with a moderate PCB size. Distinctive features - low power consumption and a wide range of operating temperatures. This design works on the basis of a DC / DC converter in Charge Pump mode. You can switch from single-channel to multi-channel mode without adjusting the basic power supply parameters.
The main features of the product include:
You can connect single or multi-channel analog inputs with bipolar input signals. Suitable for channel-to-channel devices as well as for inputs with group isolation.
The price of the goods is negotiable.
The product helps to measure analog signals with built-in analog inputs and convert the obtained indicators into physical values, so that later data can be transmitted over the RS-485 network. It has a baud rate from 2400 to 115200 bps. Supported protocols: DCON, OBEH, ModBus RTU, Modbus ASCII. Main technical characteristics:
The product can be purchased at a price of 5160 rubles.
Single-channel analogue device with thermal resistance, LED indication, Modbus / RTU and DCON. RS-485 interface type, there is a breakage recognition system, there is a connector and screw terminals. Quite high measurement accuracy - up to 0.05%. You can mount the device in two ways: using a DIN rail or directly to the wall. Power consumption - 1.2 W, input voltage in the range from +10 to +30 V, operating temperature - from -25 to +75 degrees.
The product can be purchased at a price of 16,718 rubles.
The device is manufactured in order to control the built-in discrete EEs using signals from the RS-485 network, which are used to connect executive structures with discrete-type control, as well as to collect information from the discrete inputs of modules and then transmit it to the network. The main feature is it supports many protocols, including DCON and ModBus RTU. The exchange rate indicator ranges from 2400 to 115200 bps.
Main characteristics:
Mounts on a wall or DIN rail.
The average acquisition cost is 5760 rubles.
The device controls the receipt of signals from the RS-485 network by means of built-in output elements, due to which the connection of executive devices with discrete control takes place. Supports a large number of protocols: ModBus RTU, OBEH, DCON, Modbus ASCII, as well as the OwenCloud cloud service. Significant exchange rate: from 2400 to 115200 bps. The dimensions are insignificant: 63 x 110 x 75 mm, the degree of protection is IP20, the permissible humidity is 80%, the temperature regime is from -10 to +55 degrees. Two mounting methods: wall or DIN rail.
The average cost of a product is 5580 rubles.
These models are designed and manufactured by manufacturers for the purpose of control over signals from the Internet by means of built-in discrete input elements, the main task of which is to connect actuators with discrete control. Exchange interface - dual Internet with 10/100 Mbit, used exchange protocols - Modbus TCP (makes it possible to make four simultaneous connections), SNMP and MQTT. The last two protocols are under development.
The Мх210 module is configured using a configurator that supports work with a group of modules. It provides the ability to have access to all parameters. The device is connected using the Ethernet or USB interface (via the microUSB connector). The use of USB does not require the use of external power supply to the module.
Works in two modes:
Maximum voltage indicators:
The turn-on and turn-off times are minimal and reach 15 ms. Operates at mains voltage from 10 to 48 V. Consumes power no more than 6 W. There is protection against polarity reversal. Works with archive files, the maximum size of which does not exceed 2 kb. The product measures 42 x 124 x 83 mm, weighs only 0.4 kg, has an IP20 degree of protection, and is wall or DIN rail mounted. The room temperature range for effective work is from -40 to +55 degrees. Relative humidity can reach 10 to 95 percent.
The basic configuration assumes the presence of the following components:
The average cost from the manufacturer is 7440 rubles.
I / O modules are the interface between the real world and the processor. Of course, the ideal picture looks like this: the processor contains absolutely all indicators of the measuring signals in any time period. But this is not yet possible to achieve, since there can be thousands of input-output channels from some devices, and the channels of the measuring plan are limited in bandwidth, therefore the measured values reach the process not when we want, but exclusively at discrete moments in time.
Several levels and options for polling the input channel have been developed and applied. The modern design of the input has its own microcontroller, thanks to which absolutely all channels are cyclically polled with the subsequent direction of the received information into the buffer. If the automatic system assumes the use of only a few modular channels, then the unused channels can be temporarily excluded from the polling process (masked). This will enable the system to operate more quickly and efficiently.
Currently, a discrete I / O module is very popular, which can be in two states: off and on. Analog I / O uses thermometers, thermocouples, universal current and voltage signals, RTDs, and so on as a signal.