The working principle of PLC user program execution stage

When the PLC into operation, their work is generally divided into three stages, namely the input sample, a user program execution and output refresh three stages. Completion of the three phases is called a scan cycle. During the entire operation, PLC's CPU to a scanning speed of repeating the above three phases. User program execution stage In the user program execution stage, PLC always sequentially from top to bottom in order to scan the user program (ladder). When scanning each ladder, and always scan the ladder to the left of the control line by the contact form, and then first left and right, the first order under the control of the line formed by the contact logic operation , then according to the results of plc analog io modules, refresh the logic coil corresponding bit in the system RAM storage area status; or refresh the output coil corresponding bit in the plc analog io modules image area of ​​the state; or to determine whether to execute the ladder Special function instructions provided. That is, during the execution of the user program, the only entry point will not change in the status and data plc analog io modules mapped area, while the other output point and soft devices plc digital io module image area or system RAM storage area The status and data are likely to change, and came in above the ladder, the program execution results came in below who will use these data ladder coil or work; contrary, ranked below the ladder, it is refreshed logic coil state or data can only scan to the next ranked above it on the program work.

PLC analog io module freely configurable data acquisition module FX2N-4DA

1) support standard modbus rtu protocol,, RS485 interface output via RS232, can and PC, PLC, touch screen like all kinds of data acquisition system.
2) plc analog io modules for all

plc analog input output io module

, communication ports with optical isolation.
3) All inputs freely configurable by software, you can connect any resistance, voltage, current, and other types of analog input module sensors, Free Transform range.
4) do not address acquisition module toggle switch is set directly by software, permanent anti-brownout protection.
Variety of auxiliary functions 5) software compensation to ensure the accuracy of data collection.
6)plc analog io modules Each CPU module can be connected to three expansion modules constitute the sub-station, a total of 32 analog input channels and 16 analog output channels.

PLC analog IO module user program execution stage works

PLC works When the PLC into operation, their work is generally divided into three stages, namely the input sample, a user program execution and output refresh three stages. Completion of the three phases is called a scan cycle. During the entire operation, PLC's plc analog input output module to a scanning speed of repeating the above three phases. User program execution stage In the user program execution stage, PLC always sequentially from top to bottom in order to scan the user program (ladder). When scanning each ladder, and always scan the ladder to the left of the control line by the contact form, and then first left and right, the first order under the control of the line formed by the contact logic operation , then according to the results of logic operations, refresh the logic state of the corresponding bit in the coil system RAM storage area; or refresh state corresponds to the plc input output modules coil bit plc analog io module image area; or to determine whether to execute the ladder by Special functions prescribed instructions. That is, during the execution of the user program, the only entry point in the I / O status and data mapping in the region will not change, while the other output point and soft devices I / O image area or system RAM storage area status and data are likely to change, and came in above the ladder, the results of its programs ranked in the following who will use these data ladder coil or work; contrast, came in below the ladder, its be refreshed logic coil state or data can only scan to the next ranked above it on the program work.

plc analog io modules is a remote site analog signal acquisition to the computer equipment

plc analog io modules is a remote site analog signal acquisition to the computer equipment, its use as a data communications bus lines, providing analog transfer function, can simultaneously eight plc analog input module to the module and bus transfer to the computer . As a result of the interface as a communication interface capable of multiple modules combination of plc analog input signal transmission more large ones, and can disperse the line configuration, using the address codes to distinguish, you can directly access protocol configuration software.

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.