In PLC, 4 20ma corresponds to 200 1000 I want to convert 200 1000 to 0 1600

If it is a Siemens 300PLC directly call the proportional library FC105, it is OK to change the upper and lower limits.

Description. The scale function takes an integer value (in) and converts it to a solid value in engineering units between the lower and upper limits (lo lim and hi lim). The Write Results feature uses the following equation:

out = [ float (in) ?k1) (k2朘1)) hi lim 朙o lim)] lo lim

The constants k1 and k2 are set according to whether the input value is bipolar or unipolar.

bipolar: Assumes that the input integer value is between ?between 7648 and 27648, so k1 = ?，k2 = +

unipolar: The input integer value is assumed to be between 0 and 27648, so k1 = and k2 = +

If the input integer value is greater than K2, the output (out) will clamp to the hi lim and return an error. If the input integer value is less than k1, the output will clamp at LO lim and return an error.

Reverse calibration can be obtained by setting the LO LIM > HI LIM. When using reverse conversion, the output value decreases as the input value increases.

PLC analog -20-20mA corresponds to -1000-1000, but I input 4-20mA current, how to write.

Analog refers to some continuously changing physical quantities, such as voltage, current, pressure, speed, flow and other signals, analog signals are signals with continuous changes in amplitude with time, usually the voltage signal is 0 10V, and the current signal is 4 20mA, which can be collected with the analog module of PLC, which can be converted into digital quantities after sampling and quantization. When it comes to analog quantity, we have to mention AI and AO, let's explain AI and AO (1) AI signal: analog input so-called analog quantity is 4-20mA or 0-10V current or voltage signal, input into DCS, after transformation, restore the original value, such as the current value to DCS display; The secondary value (5A) of the current transformer is converted into a 4-20mA signal (5A corresponds to 20mA) through the current transmitter, and is input to the DCS cabinet, and the actual current value is displayed in the DCS after conversion.

2) AO signal: Analog output is the opposite of AI, AO is DCS output 4-20mA or 0-10V signal to control the operating parameters of the equipment; For example, in the speed control process of the inverter, taking 40Hz as an example, through remote DCS control, it is considered that given the parameter value: 40Hz, the DCS also sends out a corresponding analog current value, in the range of 4-20mA (20mA corresponds to 50Hz), the signal is transmitted to the controller of the inverter, and the inverter runs at 40Hz according to the requirements.

After understanding the above knowledge, the first thing to understand is to understand the concept of analog, such as sensors, transmitters, actuators, AD converters, DA converters, etc. So what are the sensors we commonly use here? Commonly used are temperature sensors, including RTD and thermocouples, as well as pressure sensors, humidity sensors, and so on.

The sensor is used for analog input, which is used to collect external signals such as temperature, humidity, pressure, etc. Generally, the temperature probe cannot be directly connected to the commonly used analog module, and needs to be connected to a special temperature module or a transmitter. Generally, the pressure sensor cannot be directly connected to the analog module, and it is generally necessary to purchase its own transmitter or use a pressure transmitter.

Then, when the sensor and transmitter are used in combination, the non-electrical physical quantities can be converted into a uniform standard amount of electricity. That's where sensors and transmitters come in. The sensor and transmitter convert a standard amount of electricity, which is an electrical signal, and our PLC cannot directly receive the electrical signal, so a conversion is needed, that is, AD conversion, to convert the analog quantity into a digital quantity.

On our PLC side, the AD converter is actually an analog input module, and the DA converter is an analog pure output module. For the analog output, we do the analog control inverter speed, so as to control the motor speed; or analog control, servo torque and speed control; Or it is an analog quantity control to make a proportional valve in the ascending field.

20-4 = 16mA (20mA is divided into 16 equal parts, and the corresponding value of each part is 250).

2000 250 = 8 mA (2000 values should be 8 mA for the branches) 8 + 4 = 12 mA (because of the analog quantity.

It starts from 4ma, so 4ma is the corresponding ma value that must be added to the mu staring burning).

The maximum value of the conversion is related to the reference voltage, in order not to produce overflow, the reference is generally lowered a little, so that the sailor can take the full amount of the conversion, such as your A D should be 12 bits, and it should reach 1024 values normally, but you only have 1001 values, which is more than 2% worse, so the resolution will also decrease. You can use a converter of higher magnifications to achieve the resolution you want.