1 Introduction

Computerized batching system widely used belt weighing feeder and solid flow meter, etc., generally consists of two parts, one is the scale part: including the scale frame, belt, load weighing module, speed sensor, AC or DC drive motor and Tibetan speed machine, jumping switch, etc.. The second is the weighing instrument part: including weighing instrument, AC or DC speed control equipment and connecting door circuit, etc.. Multi-feed metering batching machine, some of the electronic weighing are connected to the factory's computer centralized control system for centralized control, the analog signal of the field instrumentation (such as 4-20mA current signals and computer signal transmission, susceptible to interference, transmission accuracy is low, and this method of transmission using more wires, the site installation workload, high investment. Operators in the control room do not understand the work of the field device, can not be adjusted to its parameters and fault testing.

Fieldbus (Fieldbus) appearance can solve the above problems, it is connected to intelligent field devices and automation systems, digital, two-way transmission, multi-branch structure of the communication network. It uses open, independent, digital double-question multivariate communication instead of 0 ~ 10V or 4 ~ 20mA field instrumentation analog signals. Compared with analog signal transmission, digital signal transmission has the advantages of high precision, strong anti-interference ability and more information transmission.

Fieldbus devices do not require frames and cabinets, and can be installed directly on the field rail groove. Fieldbus equipment set detection, data processing communication as a body, can replace the transmitter, regulator, recorder and other analog instruments, fieldbus equipment and computer or programmable controller PLC together, can be composed of inexpensive centralized control system, fieldbus equipment is extremely easy to install and wiring, only a cable or twisted pair, starting from the host, along the data chain from a fieldbus equipment connected to the next A fieldbus device, the use of fieldbus, automatic control system wiring, installation, commissioning and maintenance costs, you can save about 2/3 of the cable can save more than 80%.

2 Automatic dosage system introduction

In 2000, our company purchased 5 sets of belt feeding system, model MULTIDOS, a solid flowmeter (model MULTISTREAMI) and a centralized control station MULTICONTMASTER from German Schenker Company, which is used for the control of 300,000 cement moles, and all the electronic scales and the centralized control station use the field bus to communicate with each other, which was put into use formally in August, 2000. The centralized control station was formally put into use in August 2000.

Schenker scales can communicate with the fieldbus by installing a fieldbus interface board on the field equipment. Fieldbus system has four kinds of communication card options, they are 1) SE-BUSI Schenker internal bus 1, ModbusMODICOY company advocated a communication statute, 3964RS5 Siemens (communication protocol) protocol communication card; 2) CAN-Bus (Controller Local Area Network) protocol communication card; 3) INTERBUS-S internal bus protocol] Protocol Communication Card; 4) PROFIBLSDP (Process Fieldbus) Protocol Communication Card.

Fieldbus can be based on the above communication protocol and the user's needs to select the electronic scale communication card board, according to the protocol can be selected and any bit of communication with the board, through the fieldbus interface, the host computer can communicate directly with the electronic scale. If you choose to use Schenker MLLTICONT (PLC controller) centralized control station feeding electronic scale system, MULTICONT and metering secret communication must be selected SE-BUS bus.

2.1 Introduction to MIULTIDOS-type belt feeding scales

MULTIDOS type belt feeder is Shenk's new product mechatronics equipment, there is no electrical control cabinet, the use of twisted-pair shielded cable as a field bus to achieve all the control of belt scales adjusting the monitoring and signal feedback, compared with the traditional belt scales, can save a lot of cable, 2.2 MULTIDOS-type belt feeding scales of structural components

The MULTIDOS type belt feeding scale creation consists of the following parts:

1) Field mounting box, including 2 boards, namely DISOCONTSys-iemUniiVSE20100ProgramVDB20150 (electronic control device system unit, model VSE20100, software model VDB20150. equivalent to the weighing instrument in the traditional regulation and control 1 and DISOCONTFeldBusUni1SE/ modbus/3964TYPE, VSB201001 fieldbus interface unit for electronic control device for SE/MODBLS, 3964 and other communication protocols, model VSB201001 fieldbus interface board;

2)DISOCONTLOCALCONTROLSTATIONVLG20100(Electronic control device field control box, model VLC20100" for field operation)

3)FREOUENCYCONVERTERO.55KWSTARTYPEMMO5(frequency converter 0.5kw star connection, model MM05)

All these components are mounted on the frame of the scale, their protection class is IP65, in which the frequency conversion speed control device is integrated in the motor, the reducer and the motor are again integrated, and a proximity switch B10 is fitted at the end of the motor wind blade for measuring the belt speed. The belt scale using 2 load metering module B1B2, buried in the belt with a block of triangular thin iron plate (high 8cm, 2cm, bottom 12cm) using the proximity switch B12 as a runaway monitoring device, when the belt runs away from the 3cm alarm 4m to jump-stop, the belt skidding 2% can be set to alarm, but also can be set to jump-stop, effective protection of the belt scale.

2.3 DISOCONT system unit software settings

DISOCONT system unit is installed on the belt scale, there is no intuitive human-computer interface like the general weighing instrument. It is necessary to use a laptop to install the DISOCONIEasyServe maintenance software, through a special RS232 communication cable, to set the parameters of the belt scale, and then calibrate the belt scale. The calibration parameters are revised on site by means of a laptop computer.

DISOCONT system unit software settings and other models of Schenker scales is the biggest difference between the communication fieldbus parameter settings, first of all, you should select the type of communication protocol, such as selecting SE-BI and then according to the SE-BUS, fill in the other relevant parameters TimeuutHost10s (host communication timeout I0s) Cumm-ErrorHostiG (host communication), SE-ErrorHostiG (host communication), SE-ErrorHostiG (host communication), SE-ErrorHostiG (host communication), SE-ErrorHostiG (host communication), and SE-BUS (host communication). Cumm-ErrorHostiG (host communication error ignored), SE-BUSAddress2 (SE bus address 2) and so on.

After setting the parameters of the DISSOCONT electronic control device, it can communicate with the host MULTICONTMASTERI centralized control station through the field bus SE-BUS, and transfer the relevant parameters of the belt scale to the host for display, such as the cumulative number of feeding quantities of the electronic scales, the measured load of the electronic scales, the running speed of the electronic scales, the actual feeding value, the actual set value and the alarm and trip-stop information about the belt scale, etc. The host MULTICONTMASTERI centralized control station can also communicate with the host MULTICONTMASTERI centralized control station. The MLLTICONTMASTERI centralized control station of the host computer! Control functions are to set the total amount of feed, the dosage ratio of each scale, select the start and stop of each scale when a scale jump-stop, all interlocked jump-stop and so on.

3 Operation status and benefits

MULTICONTMASTER centralized control station fieldbus SE-BUS and MLLTIDOSSets of belt feeders and a solid flow to let MULTISTREAM communication, from August 2000 into use so far performance is stable, the physical calibration accuracy is guaranteed to be within 0.5%, and the scale of the adjustment range is relatively large, range can be appropriately modified, because the frequency converter has 10 The scale has a wide range of adjustment, and the range can be modified appropriately because the frequency converter has 10 grades of speed adjustment. The scale has many protection functions and accurate dosage. The centralized control station also has two electric ears, forming a good mill dosage system. The centralized control station with fieldbus saves a lot of input and output interface modules and a lot of control cables compared to a normal centralized control station, saving investment. At the same time, MULTIDOS belt scales use a frequency converter integrated in the motor, eliminating the interference of the frequency converter and the cables from the frequency converter to the motor to other equipment.