重量是生活中一个重要的单位，那么在工业上它更是非常重要。生产环节中加了多少公斤的原料？产生了多少公斤的废品等等等等……这些数据都是支撑着整个工厂良好运行的必要元素。
Weight is an important unit in life, and it is even more important in industry. How many kilograms of raw materials are added to the production process? How many kilograms of waste are produced, etc… These data are necessary elements to support the good operation of the entire factory.
那么在工业上如何计算重量呢？我们需要使用称重传感器！
So how to calculate weight in industry? We need to use load cells!
称重传感器的原理是在被测物体上的重力按一定比例转换成可计量的输出信号。
The principle of the load cell is to convert the gravity on the measured object into a measurable output signal in a certain proportion.
西门子称重传感器的测量采用应变式原理，应变片被固定在弹性体上。外力的作用导致弹性体产生形变，在弹性体上的应变片随之产生形变。由于应变片外部形状的变化，其电阻值也会相应发生变化。左上角和右下角应变片被压缩，电阻薄膜变短，阻值变小。右上角和左下角应变片被拉伸，电阻薄膜变长，阻值变大。对于每只称重传感器，至少4个应变片被连接在一起组成一个惠斯通电桥。当传感器受力导致应变片电阻发生变化时，电桥不平衡。 在激励电压不变的情况下，输出信号的大小与传感器受力成正比。
The measurement of Siemens load cells adopts the strain gauge principle, and the strain gauge is fixed on the elastomer. The action of external force causes the elastic body to deform, and the strain gauge on the elastic body subsequently deforms. Due to changes in the external shape of the strain gauge, its resistance value will also change accordingly. The strain gauges in the upper left corner and lower right corner are compressed, the resistance film becomes shorter, and the resistance value becomes smaller. The strain gauges in the upper right corner and lower left corner are stretched, the resistance film becomes longer, and the resistance value becomes larger. For each load cell, at least 4 strain gauges are connected together to form a Wheatstone bridge. The bridge is unbalanced when force is applied to the sensor causing the resistance of the strain gauge to change. When the excitation voltage remains unchanged, the size of the output signal is proportional to the force on the sensor.
称重传感器一般可以连接PLC或者二次表进行示数。 The load cell can generally be connected to a PLC or a secondary meter for display.
对于四线制传感器，只有下图黑色所示的四个电缆，其中EXC+和EXC-是称重模块给传感器的激励，SIG+和SIG-为称重传感器的输出；对于六线制传感器，会多出两根红色的线，SENSE+和SENSE-它们的作用是什么呢？这两根线是做补偿用的，当传感器和称重模块的距离较远时，这两根线会进行补偿，进而使得测量结果更精确一些。
For a four-wire sensor, there are only four cables shown in black in the figure below. EXC+ and EXC- are the excitations given by the weighing module to the sensor, and SIG+ and SIG- are the outputs of the weighing sensor. For a six-wire sensor, there will be more Take out two red wires, SENSE+ and SENSE-. What are their functions? These two lines are used for compensation. When the distance between the sensor and the weighing module is far, these two lines will be compensated, thereby making the measurement results more accurate.
在实际现场的使用中，因为工况比较复杂，使得称重传感器和称重模块之间的距离较远，称重模块给传感器的供电电压假设为6V，那么由于线路的损耗，该激励信号到达称重传感器时小于6V，在同样受力情况下，传感器的输出信号与供电电压成正比，所以称重模块通过一个高阻抗回路将传感器侧实际的供电电压反馈给称重模块，称重模块通过内部的比较器对输出的供电电压进行调节。 称重模块可以连接四线制和六线制传感器都可以。 如果连接四线制传感器，需要在接线盒或者称重模块侧将SENSE+与EXC+短接，SENSE-与EXC-短接。
In actual on-site use, because the working conditions are relatively complex, the distance between the weighing sensor and the weighing module is long. The power supply voltage of the weighing module to the sensor is assumed to be 6V. Then due to the loss of the line, the excitation signal reaches The load cell is less than 6V. Under the same force, the output signal of the sensor is proportional to the power supply voltage, so the weighing module feeds back the actual power supply voltage on the sensor side to the weighing module through a high impedance loop. The weighing module passes An internal comparator regulates the output supply voltage. The weighing module can be connected to both four-wire and six-wire sensors. If you connect a four-wire sensor, you need to short-circuit SENSE+ and EXC+, and SENSE- and EXC- on the junction box or weighing module side.
For the use of PLC to connect load cells in factories, we usually have two ways to implement it;
一、使用称重传感器加二次表加PLC的模拟量输入，为什么需要加二次表呢？因为传感器是由物体重量压弯而产生一个mv级电压信号，PLC无法直接读取，所以需要二次表进行转换，一说到转换大家都知道一定会有损耗，这个损耗其实不是很大，但是对于精确测量就会产生很大影响，我以前曾经做过10g精度的设备，这个损耗就是结果影响就很大了，所以这一方法的有点是便宜，对于PLC系统没有太大的要求，因为世面上98%的PLC都带模拟量输入功能。但缺点是无法应用在精度要求较高的情况下。
1. When using a load cell plus a secondary meter and the analog input of the PLC, why do you need to add a secondary meter? Because the sensor is bent by the weight of the object and generates an mv level voltage signal, which cannot be read directly by the PLC, so a secondary table is needed for conversion. When it comes to conversion, everyone knows that there will be loss. This loss is actually not very big, but It will have a great impact on accurate measurement. I have made equipment with a precision of 10g before, and this loss has a great impact on the results. Therefore, this method is cheap and does not have too many requirements for the PLC system. Because of the world’s 98% of PLCs on the Internet have analog input functions. However, the disadvantage is that it cannot be applied in situations with high accuracy requirements.
二、最精确的方法，也是最昂贵的方法，使用称重传感器加PLC称重模块进行测量。
2. The most accurate method, and also the most expensive method, is to use a load cell plus a PLC weighing module for measurement.
这种方式是最精确的，因为PLC连接自己的模块是没有损耗的，而且这种方式的读取速度也是非常快的，可以应用在各种复杂的场合中。
This method is the most accurate, because there is no loss when the PLC connects its own modules, and the reading speed of this method is also very fast, and can be applied in various complex situations.
那么它的缺点是对于PLC系统有着很大要求，首先PLC需要使用带称重模块的，而一般称重模块的价格都比较高，而且使用一个新的称重系统以前需要对它进行校准，一旦称重传感器损坏了更换的话，也需要重新校准，而西门子的各个系列的称重模块的校准都不是很简单，需要一定的经验和技术，这个以后我们还会讲解的；所以这一技术不适合新手。
Its disadvantage is that it has great requirements for the PLC system. First of all, the PLC needs to be equipped with a weighing module, and the price of the general weighing module is relatively high, and it needs to be calibrated before using a new weighing system. If the load cell is damaged and replaced, it will also need to be recalibrated. The calibration of each series of Siemens weighing modules is not very simple and requires a certain amount of experience and technology. We will explain this later; so this technology is not suitable Newbie.
As a precise measurement unit, attention must be paid to its use, otherwise it may lead to inaccurate measurement or even damage.
一、安装时需要非常注意，否则容易损坏传感器 1. Pay great attention when installing, otherwise the sensor may be easily damaged.
称重传感器的弹性体的制作材料主要还是合金的铝材，所以出现任何一点震动导致的冲击或者是发生掉落的情况都会导致出现非常大的数据输出误差。比如一个量程为10kg的传感器，如果不小心给了它15kg左右的力，就有可能永久损坏它，因此，安装称重传感器一定要做到轻拿轻放。
The elastomer of the load cell is mainly made of alloy aluminum, so any impact caused by vibration or falling will lead to very large data output errors. For example, if a sensor with a measuring range of 10kg is accidentally given a force of about 15kg, it may be permanently damaged. Therefore, when installing a load cell, you must handle it with care.
二、安装时严格按照它的设计要求 2. Strictly follow its design requirements when installing
根据设备的工艺，或者水平安装或竖直安装，但传感器的称重部分一定要与被测物体严密吻合，切称重部分和被测物体不能接触器其他着力点，否则会导致测量不准。
Depending on the technology of the equipment, it can be installed horizontally or vertically, but the weighing part of the sensor must be closely matched with the object being measured. The weighing part and the object being measured must not come into contact with other focus points of the sensor, otherwise it will lead to inaccurate measurement.
三、有时需要使用三个甚至多个传感器共同测量同一物体，这些传感器与称重装置的接触面必须水平，否则受力不均，影响测量结果，虽然轻微的水平面倾斜可以通过接线盒里的电阻调节，但调节能力有限，而且也不利于效称，所以安装时尽量保持水平。
3. Sometimes it is necessary to use three or even more sensors to measure the same object. The contact surface between these sensors and the weighing device must be horizontal, otherwise the force will be uneven and the measurement results will be affected. Although a slight tilt of the horizontal plane can pass through the resistor in the junction box. Adjustment, but the adjustment ability is limited, and it is not conducive to efficiency, so try to keep it as level as possible during installation.
一、接线盒；在使用多个称重传感器时，接线盒是一个必要的工具，它可以将多组称重数据统一到一起，减少称重模块的工作量。
1. Junction box; when using multiple load cells, the junction box is a necessary tool. It can unify multiple sets of weighing data together and reduce the workload of the weighing module.
但是在使用过程中，它也是很容易出问题的。 However, it is also easy to cause problems during use.
首先要注意防尘放水防静电，其次在使用中要注意每一个端子的含义，切忌接错线。
First, pay attention to dust, water, and anti-static. Second, pay attention to the meaning of each terminal during use, and avoid connecting wrong wires.
二、电缆的连接和屏蔽 2. Cable connection and shielding
传感器的信号最终还是通过电缆进行传输，而且对于如此高精度的信号，有一点干扰都会导致数据的不稳定。
The sensor signal is ultimately transmitted through cables, and for such a high-precision signal, any interference will cause data instability.
因此连接时需要严格按照上图进行施工。 Therefore, the connection needs to be carried out strictly in accordance with the above diagram.
三、编程的注意事项，滤波是否可以使用？ 3. Precautions for programming, can filtering be used?
在实际的工业现场会存在很多干扰，那么很多人都习惯使用程序手段进行滤波，但是对于称重也是可以使用的，但是需要注意的是；滤波会产生信号的滞后性，如果只是单纯的观察和测量则没有问题，但如果是计算或者是使用测量结果进行控制那么就会导致称重结果不准确，这里大家需要注意。
There will be a lot of interference in actual industrial sites, so many people are accustomed to using program means for filtering, but it can also be used for weighing, but it should be noted that filtering will produce signal lag. If it is just simple observation and There is no problem with measurement, but if it is calculated or the measurement results are used for control, it will lead to inaccurate weighing results. Everyone needs to pay attention here.
