How to extend the analog inputs and outputs - PLC scaling examples

Analog IO connection either 4-20mA or 0~10V pressure sensors, level probe and other analog devices. Since the programmable logic control plc or control engineer, you will need to get some knowledge from the PLC IO expansion modules, analog signal. Zoom helps the analog value measurement unit (pressure, level, etc.).
Most industrial applications often require measurement of engineering units to provide more meaningful data.
Input method as an example
If we want from our analog cards 32000 (engineering units) measured from the tank level 0-65 m so our L = 0, H = 65 maximum. From the analog input current value A13454. Now, if we calculate using our formula, we'll get on the current level of 23.7 meters.
Now the situation looks slightly different analog output module.
Digital PLC program must calculate the value is sent to the plc analog input output io modules. There are many ways to do this, but most industrial applications, if you use the measuring engineering units understanding easier.

Analog IO module added to the PLC line

Directly increases the Click PLC line of discrete and Analog IO module. 24 V DC combination of discrete modules include 8:00 DC input / 8:00 DC sinking or sourcing output mode, four o'clock DC input / 4:00 relay output mode.
24 V dc four-channel analog input module, 13 resolutions, including 0-20 mA current input, 0~10V voltage input version; 12 resolution four-channel output module 4-20 mA current, 0~10V voltage versions. Also increased in the current and voltage versions of the four-channel input / 2 channel analog output module. The module has 13 inputs and 12 resolutions resolution output.
Four-channel RTD and thermocouple module with 16-bit resolution, also increased. RTD input module accepts Pt100, Pt1000's, JPT100, CU10, Cu25 heat and Ni120 elements; addition, support resistance range. Thermocouple input module supports nine types of thermocouples and voltage range.

the advantages of PLC analog IO module

First, it allows you to find plc IO module close to being monitored or controlled process. This greatly improves noise immunity, as weak sensor signals are transmitted long distances before converted into a digital signal through a noisy plant environments. Omega universalplc analog IO modules using MODBUS RTU / ASCII protocol, which is supported by a simple majority of the 2-wire RS485 programmable logic controller. The second advantage is, PLC analog input plc significantly reduces the wiring in the main control panel, saving time and money, while repairs and upgrades are necessary. Adding additional sensors and control signals are connected to the RS485 link and modify the PLC program has been installed, use the new I / as easy as O. In addition, plc analog input output module, you can expand your process control system beyond the local I / O capability of the PLC. You can add a thermocouple, RTD, pressure and flow sensors do not support these types of input of a PLC. With PLC analog IO modules, your application is no longer dependent on the choice of the controller.

Analog Output Module

plc module is normally used to drive the analog output voltage analog actuator (e.g., a proportional control valve) and a current loop drive actuators and various instruments. Each board depending on the type of output, typically supports multiple channels. The output channels can be isolated individually or grouped isolation.

 In the above diagram, we give a basic serial architecture, using I2C or SPI serial bus, the on-board processor through the isolator serial control information sent to the specified channel DAC, converted to output module plc. If you need to isolate each output separately, you will need to provide a way for each channel output DAC; If you allow grouping isolation, DAC subsequent distributor can keep hold capacitor DAC output until the next refresh. After the DAC, there are usually additional calibration circuit and an output buffer for fine tuning signal to provide the necessary voltage or current drive.

Plc Input / Output Modules Description

The type of input modules used by a PLC depends on the type of input device. For example, some respond to digital inputs, which are eitheronoroffwhile others respond to analog signals. In this case, analog signals represent machine or process conditions as a range of voltage or current values. The plc digital input output module converts signals into logic signals that the CPU can use. The CPU evaluates the status of inputs, outputs, and other variables as it executes a stored program. The CPU then sends signals to update the status of outputs.
Output modules convert control signals from the CPU into digital or analog values ​​that can be used to control various output devices. The programming device is used to enter or change the cpu modules program or to monitor or change stored values. Once entered, the program and associated variables are stored in the CPU. In addition to these basic elements, a PLC system may also incorporate an operator interface device to simplify monitoring of the machine or process.

distributing plc analog io modules

  You can install the plc analog io modules locally in the same chassis as the controller. Additionally, through the use of I/O communication networks, you can distribute the plc analog output closer to the sensors and actuators, reducing your wiring costs.
  In-Cabinet (IP20) distributed plc analog io modules can be placed throughout your application and requires an enclosure. Our In-Cabinet Modular pulse input module plc products let you select the exact mix of I/O interfaces and communication adapters to fit your needs, providing greater flexibility in designing your system. In addition to a wide range of analog, digital, and specialty modules, we provide in-cabinet I/O options for extreme environments, I/O for safety systems, and intrinsic safety (IS) I/O that can be distributed throughout hazardous areas.

plc analog output module acquisition module in the Control System

In the industrial production process, there are many of the continuous change, such as temperature, pressure, flow, level and speed are all analog. In order to deal with analog programmable controller must achieve A Analog (Analog) and Digital (Digital) between the A / D conversion and D / A conversion. PLC manufacturers are supporting the production of A / D and D / A converter module, the programmable logic controller for analog control. And in the actual IO module plc environment, the system often plc analog output modules weak current or voltage signal (mV or mA level), and generally with a load capacity is low. Direct implementation of the remote monitoring device is used, often because of the attenuation caused by long-distance transmission signal, distortion, and sometimes due to industrial automation plc external signal errors caused by signal interference, affecting the normal operation of the entire system. This requires that we ask for RTD, thermocouple temperature signal and the current and voltage signal acquisition, the digital output port via RS485 serial interface using standard communication protocols to transfer data to the PLC.