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The development of digital sensor and digital instrument technology, digital weighing system has gradually become the new darling of weighing technology field, with its high efficiency, adapt to the scene debugging capability and other advantages are emerging in weighing technology field. Among them, the application of the truck scale and the static rail scale is the most common.
Digital truck scale because of the use of digital weighing technology, there is a big difference in forms of traditional analog truckscale first, digital truck scale instrument (or computer) and the interface between the sensor belongs to the digital communications (usually RS485 communication interface), receiving instrument direct digital signal sensor is sent, the length of the transmission line up to 1000 meters; and between the ordinary analog vehicle weighing instrument and sensor interface to analog interface, analog signal receiving sensor instrument first, and then the A/D conversion after further processing, the transmission distance is 20 ~ 30 meters. Secondly, due to the digital truck scale receives the digital signal, adjust the angle difference by directly in the instrument weighing management software to deal with, rather than analog truck that need to adjust the connection box in the potentiometer to adjust the angle between the objective. These obvious differences also determine the digital truck scale in the installation and debugging there are many different from the analog truck scale place.
Two 、 installation and debugging method of digital truck scale
As already mentioned, digital truck scale is used in digital sensor, sensor output directly into digital signals, so the RS485, consisting of truck scale can use digital weighing instrument, can be directly used computer with special software. There are no differences between the two methods in installation and debugging. For the convenience of description, the following figures are illustrated by digital instruments.
First, the digital instrument and digital sensor interface connection: This is the digital truck scale installation and debugging key.
First, define the definitions of the pins in the interface. Digital sensors generally use RS485 communication interface, but due to differences in usage and design habits, there are differences between the two wire system and the four wire RS485 interface, and the connection needs to be distinguished. RS485 interface two wire belongs to at most one way we see in the routine use of the sensor output a total of 5 lines, respectively: shielding wire, power is, (GND), receiving / sending is positive (A/T+) and receiving / sending negative negative (B/T-), can be equipped with digital instrument two wire and four wire RS485 interface.
Four wire RS485 interface sensor, general output line for 7 roots, including: shielding line, power supply, ground wire (GND), receive positive (+ R), receive negative (-R), send positive (+T), send negative (-T), etc.. Four wire RS485 interface sensor, generally can only connect to provide 4 wire interface instrument, strongly recommended not to use in the two wire interface digital instrument, otherwise there will be data communication failure. The interface is shown in figure 2.
Note: no matter what kind of wiring, the wiring must first ensure the power line is connected correctly, especially the installation of the entire scale after electrifying debugging, must carefully check and check the correctness of the power line connection, otherwise easily cause damage to the internal circuit of digital sensor.
Three, digital truck scale before the installation work (preliminary preparation, debugging):
Before installation, the following preparations should be done carefully to facilitate the installation and commissioning.
1. first determine the speed, data format, and communication string format used by the digital sensors in line with the internal definitions of the digital instruments. Digital instrument and digital sensor based on RS485 communication link, so the communication speed (baud rate), data format (including data bits, stop bits, parity etc.) must be consistent; at the same time, data communication and command must be the correct analysis, communication string format must also receive a string format consistent with the instrument. For example: digital sensor HBM, with 9600 and 19200 of the two baud rate, 7 bit and 8 bit two data bits, no parity, parity is odd and even parity in 3 ways, communication string format also has the Formate1 ~ Formate4, before use if you are not sure to clear, easy for later debugging a great deal of trouble.
If the parameters are inconsistent, you must first set up the digital sensor's communication, baud rate and data format with the meter before installing. Some digital instruments, such as Yaohua's XK3190-DS1, DS2 and so on, have the function of automatically detecting and setting up communication parameters. The digital sensors are connected directly with each other to complete the communication parameter setting.
2. determine the self filtering strength of the digital sensor.
There is no fixed standard for the filtering strength of digital sensors, which can meet the requirements of the field. According to the field experience, we generally suggest that the filter intensity of the sensor can be set at 1~3 levels lower than the filtering intensity of the final truck scale. The digital sensor HBM as an example, if we use the final filtering strength of the vehicle scale is 5, it can be set in the digital sensor HBM below level 4 (above 0.5Hz), subsequent filtering by instrumentation, instrumentation filter can be set in 3 grade 3 or above.