Load Cell Junction Box Background Technology:
The weighing junction box is a device that outputs one signal after adjusting the signals of multiple load cells. It is divided into analog junction box and digital junction box. The analog junction box is a device that outputs a voltage signal after connecting the signals of multiple load cells in parallel. The digital junction box is a device that converts the signals of multiple load cells into digital and analog, and outputs digital signals through serial communication.
Weighing junction boxes are widely used in mass measurement. In particular, some large scales need to install multiple load cells to complete the measurement, such as truck scales, platform scales, hopper scales and other scales, etc. need to install 4 or more load cells to complete the measurement work. In order for the host computer instrument to process the weighing signal, it is generally necessary to use a weighing junction box to synthesize multiple load cell signals into one signal. Therefore, the weighing junction box is an indispensable equipment for various weighing instruments.
The principle and application of the junction box of the electronic platform:
Analog Junction Box:
The junction box used by the analog weighbridge is analog, which can connect analog load cells and analog weighing display instruments. No matter how many load cells are used on the scale, they are generally connected in full parallel, and each load cell must be connected in parallel to work. The ratio of the sensitivity of the load cell to its output impedance is required to be equal, but in the actual production of the component, the difference between the sensitivity and the output impedance is inevitable, which will lead to an error in the weighing result of the weighing system, so the junction box The function is also to make the output of each Ningbo Goldshine intelligent load cell consistent. Therefore, from this point of view, the junction box is equivalent to a passive resistance network, and adjusting an adjustable resistance is equivalent to changing the output impedance of the load cell connected to it, so that the load cell can realize full parallel operation.
Digital Junction Box:
The floor scale equipment is constantly developing towards digitalization, and naturally its Ningbo Goldshine intelligent junction box is also making continuous progress. The digital junction box converts the analog signal generated by the analog load cell into a digital signal, and transmits the data to the weighing display instrument after processing. According to the difference in circuit structure, this type of junction box is divided into single A/D and multi-channel A/D forms. Single A/D is to connect multiple analog load cells to an A/D conversion circuit, and multi-channel A/D The junction box is equipped with multiple analog load cell inlets and a power communication port. It has multiple A/D conversion communications and can be connected to multiple load cells on the weighing platform. The digital junction box is an essential part of the digital weighbridge.
The weighing junction box currently used has the following problems:
Whether it is an analog weighing junction box or a digital weighing junction box, the multi-channel load cell signals are synthesized into one signal through parallel connection. The digital weighing junction box sends the synthesized signal to the host computer after digital-to-analog conversion, while the analog weighing junction box directly sends the synthesized voltage signal to the host computer. Due to the different parameters such as the sensitivity of the load cell, it is necessary to adjust the potentiometer on the junction box before the parallel connection of each load cell signal to adjust the voltage output value of each load cell. However, this method is often difficult to accurately adjust the voltage output of the input load cell, and there is a large error, which affects the weighing accuracy.
The working mode of Ningbo Goldshine intelligent weighing junction box currently used cannot judge the working status of each load cell after the signal of the load cell is synthesized. If a load cell fails, the upper computer instrument cannot recognize it, and it is only reflected as The weight to be weighed is transformed, thus producing erroneous weighing results.
In order to obtain unjust profits, some people install a cheating circuit on the load cell, and change the weighing weight by directly changing the output voltage of the load cell. However, the current working method of the weighing junction box cannot determine whether there is a cheating circuit. An opportunity for criminals to take advantage of.
Due to the above-mentioned defects, the weighing junction box restricts the improvement of weighing accuracy during the use of the weighing instrument, and at the same time it is difficult to detect the failure of the load cell in time, which often causes large economic losses.
Eight steps for weighing junction box installation:
When we decide to buy an electronic truck scale and choose a good truck scale, the first thing to do is the basic engineering installation steps of the electronic truck scale, that is, the electronic
platform scale, which is divided into eight steps to complete.
1: The basic structure of the electronic truck scale (weighbridge) is divided into two types: shallow foundation pit and no foundation pit. Our company provides users with scheme drawings according to their needs.
2: According to the basic plan drawings provided by the user, combined with the geological conditions of the site, the user proceeds to the construction drawing plan. Special attention must be paid to three issues in the construction plan:
2.1: Basically, the bearing capacity of plain soil (earth endurance) shall not be less than 20t/m2. If the site geological conditions do not meet this requirement, reinforcement must be done.
2.2: Basic excavation must be dug below the local permafrost line.
2.3: For shallow foundation pits, drainage channels must be planned. There is basically no foundation pit to consider the surrounding drainage problems to ensure that the truck scale will not be submerged in the water due to rain.
3: The vertical and horizontal steel mesh in the basic concrete needs to be bundled with 16# iron wires for more than 50% of the intersection points, and connected to each iron floor with steel bars (used as the ground wire of the load cell).
4: The embedded parts (iron bottom plate, anchor bolts, angle iron edge protection, etc.) in the basic construction shall be prepared by the user. Measures must be taken during construction to ensure the correct position of the anchor bolts and the iron floor. For this reason, it is suggested to adopt the method of secondary grouting for positioning, and it is necessary to ensure that there is no cavity between the iron bottom plate and the concrete. During the construction, it is necessary to ensure that the levelness and elevation of each iron floor meet the requirements of the basic plan drawing. The contour difference of the center of each iron bottom plate shall be less than 2mm, the horizontal inclination of the iron bottom plate shall be less than 1/500, and the diagonal deviation of the center distance of each iron bottom plate shall be less than 2mm.
5: After the basic construction is completed, attention must be paid to maintenance. In order to shorten the construction period and maintenance time, it is allowed to add “early strength agent” and other measures to the concrete during construction. The weighing platform shall not be installed when the concrete has not reached the strength of the scheme.
6: The weighing room scheme of the electronic truck scale is determined by the user according to the actual needs: a grounding wire and 220V power supply must be installed in the weighing room for the use of the weighing control instrument. The weighing room must be close to the weighing platform. In special circumstances, please inform our company in advance.
7: Users in the northern region should consider heating in winter. Users who have the conditions use air conditioning or heating, and coal stoves are not allowed in the weighing room.
8: The weighing signal cable leads from the weighing platform and enters the weighing room through a metal tube. It is recommended to use a 1-inch metal tube and at the same time pass through the iron lead of the cable.
Ningbo Goldshine Intelligent Co., Ltd. is committed to providing users with high-quality weighing instruments, advanced weighing solutions and first-class after-sales service, and has built the company into a comprehensive electronic weighing instrument supply platform enterprise. Customize products according to customer needs and provide system weighing solutions. The company has a complete sales management and pre-sales after-sales service system, with a professional sales team and high-quality after-sales service, to provide customers with meticulous and thoughtful product services.