Application of the hottest Fieldbus in the product

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The application of Fieldbus in the production line of engine cylinder

the field communication network of programmable controller (PLC) is an important direction of PLC development and application, which also makes PLC obtain greater application benefits in the industrial field. At present, there are many kinds of fieldbus standards that can be implemented by communication low-voltage appliances, among which composbus/s fieldbus is a widely used open fieldbus that can connect various sensors and actuators at the bottom. Omron SYSMAC cjplc is a small, high-speed data transmission new PLC, which can form a composbus/s bus as the master station according to needs. The following is a brief introduction of its application in the engine block production line of diesel engine company

2. composition of the production line

the 190 to 210 processes of the engine cylinder block of the diesel engine company consist of five special machines and conveying devices, which are used to uniformly load and unload parts. The production line requires that each machine tool can not only be adjusted independently and processed automatically by a single machine, but also five machine tools can be processed simultaneously. An operator can operate five machine tools at the same time by operating on the first machine tool console. This requires that the relevant interlocking signals between the five machine tools be transmitted to each other, so it puts forward high requirements for the electrical control system

3. Overall scheme of control system

the design principles of electrical control system are: (1) the system should be progressiveness; (2) Stable and reliable; (3) Safety; (4) Scalability; (5) Maintainability and operability; (6) Economy; (7) Habit of use. According to the characteristics of the production line and the requirements of the electrical control system, we adopt the fieldbus distributed control scheme. That is to change the previous centralized control mode in which the i/o module and controller devices are all in a group of electric control cabinets, distribute the controller devices to each single machine, and connect them with the PLC of the main control cabinet through the bus to form a unified electric control system

3.1 characteristics of composbus/s fieldbus:

(1) it is a perfect high-speed on/off bus in mechanical system

(2) special cable saves wiring, without terminal conversion unit, which is convenient for installation

(3) when connecting PC, slave station and i/o equipment, it can save the cost and time of establishment and maintenance of each system as wiring

(4) it is easy to connect the sensor and the slave station unit

(5) t branch allows simple system expansion

(6) the cycle period is up to 1ms, which can be expanded to 32 slave stations and 256 i/o points

3.2 hardware selection

the control core of the electric control cabinet is all PLC products of OMRON company. When the performance and speed meet the requirements, the optimal performance price ratio is pursued. Therefore, the PLC adopts cj1m and CPM2AH series, the fieldbus adopts composbus/s, the master station unit is cj1w-srm21, and the slave station link unit is cpm1a-srt21. In order to reduce signal reflection and make the network stable in commercial utilization, terminal resistors srs1-t are connected at both ends of the trunk line, the central processor (CPU) of the master station adopts cjim-cpu11, and the power supply unit adopts cj1w-pa202

3.3 main functions of the system

according to the design principle of "centralized management, integrated monitoring and segmented control", according to the actual situation of the cylinder line, the composbus/s bus is used to connect the distributed i/o stations, operation panels, etc., and the main controller (cj1m) with fieldbus interface is used to realize the combination and single machine control of the equipment in each process section, so as to meet the production requirements

(1) automatic control function

according to the process requirements, it can realize the sequential control, startup, shutdown, fault shutdown, alarm

of the cylinder line

(2) manual/automatic switching function

generally, the system operates under automatic control. When the equipment needs to be repaired, maintained and debugged, the system can be switched from automatic state to manual state, and the independent start and stop operation of the equipment can be realized through the specific buttons of the equipment

(3) there are a variety of safety measures

it is certain that after-sales service is to reduce the loss caused by equipment failure. Each control circuit, each motor, each power circuit and each electric control cabinet on the control system are equipped with multi-level protection measures, which is safe for people and equipment

(4) it has the function of automatic fault diagnosis and alarm, as well as the necessary ability of automatic fault processing. In case of

fault, there is an alarm light

4.control mode of composbus/s Fieldbus

4.1 composbus/s bus wiring is shown in Figure 1

4.2 machine tool 1 is the master station, and machine tool 2 to machine tool 5 are the slave stations of machine tool 1

(1) each SRT connection word has 8 point input and 8 point output, and is assigned its own node number

(2) the wiring is a dual core VCTF cable, the communication baud rate is 750kbps, and the maximum communication distance is 100m

(3) address 1million lithium-ion electric vehicles need at least 50000-60000 tons of battery grade graphite distribution: the dip switch on srt21 is used to set the node number and maintain or eliminate communication output errors

node number setting: as shown in figure 2:

set the node number of cpm1a-srt21 on machine tool 2 to 0

the node number of cpm1a-srt21 on machine tool 3 is 1

the node number of cpm1a-srt21 on machine tool 4 is 2

the node number of cpm1a-srt21 on machine tool 5 is 3

4.3 the 60 point PLC (cpm2ah-60cdr-a) is selected for machine tool 2 to machine tool 5. The input address of slave station cpm1a-srt21 is assigned as 003 and the output address is assigned as 013

when the first pin of DIP switch in cj1w-srm21 is off, the input and output addresses of each machine tool in CJIM are assigned as shown in figure 3:


machine tool 1 receives the total stop signal from machine tool 2 to machine tool 5 and transmits the total stop signal to each machine tool at the same time. The PLC program in machine tool 1 is shown in Figure 5:

where 009 is the total stop signal (total stop button) of each machine tool, and the output place of each machine tool

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