1. What is loss protection? What methods are commonly used to achieve this protection in relay contactor control lines?
The so-called voltage loss protection means that when the power supply voltage is too low or suddenly disappears, the motor automatically stops running, and the motor does not start automatically when the power supply returns to normal. In the relay contactor control circuit, the contactor and button control mode is usually adopted, or the zero voltage relay is used.
2. What is the PLC device? What are the characteristics?
Each input/output relay, counter, timer, etc. that the PLC provides to the user and each memory unit can be specified by a program (ie, software), called a device; each device has its functional characteristics and fixed address, soft The number of components determines the size and data processing functions of the PLC system.
3. Briefly describe the working principle of the programmable controller?
The PLC uses a cyclic cycle scan, centralized input and centralized output mode of operation.
Input sampling phase: The PLC reads all input states and data in turn by scanning and stores it in the corresponding storage unit in the I/O image area.
User program execution phase: The CPU scans the user program from top to bottom, from left to right, executes each instruction step by step or determines the execution of certain special function commands according to the logical operation result of the control line.
Output refresh: The result of the operation in the program execution phase is stored in the output image area and not directly sent to the output port. Wait until the output refresh phase and then uniformly refresh to the external output port.
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1. FX2 series PLC input and output response time are (10ms)
2.FX2 series PLC control system for temperature control, scalable (FX-2AD-PT)
3. FX2-16MT is the transistor output, MR is the relay output, and MS is the (thyristor output).
4. FX2 PLC read special expansion module data should be used (FROM).
5. The central processing unit of Mitsubishi FX2 series PLC mainly uses (general purpose microprocessor) chip.
6. FX2 series PLC control system for analog input control, expandable special function I / O module is (FX-4AD).
7. In the FX2 series PLC, when a single button start switch is encountered, it can be implemented by (ATL) command.
8.T belongs to a word, (bit mixed) component.
9. Cage three-phase asynchronous motor step-down starting method: Y-delta step-down starting, stator string resistance or reactance step-down starting, autotransformer step-down starting and (extreme-edge triangular step-down starting).
10. The number of I/O points of the medium-sized PLC is 256 points or less and the storage amount is 2-8K steps; the number of points is between 256-2048, the stock is 8-32K steps; the number of points is above 2048, and the storage amount is (32K steps).
11. PLC host control The hub CPU is mainly composed of (array), (controller), (register).
12. PLC provides (256) special-purpose auxiliary relays.
13. The high-speed counter in the programmable controller is independent of the scan cycle, and its counting operation is performed according to (interrupt mode).
14. Data communication between the FX2 series PLC host and the special function I/O module is performed by the (FROM/TO) instruction.
15. The most fault-tolerant network in the WAN topology is the (mesh) topology.
16. Serial communication standards commonly used in industrial networks include (RS-232C) serial bus standard, (RS-422A) serial bus standard, and (RS-485) serial total standard.
17. Low-voltage electrical equipment works at less than (1200V) DC less than (1500V).
18. Programmable Logic Controller PLC initially only has (logic control), (sequence control), (timing), (count) and other functions, mainly replacing (relay control).
19. The FX2 series PLC provides 1000 status controllers, which are dedicated programming devices for the (SFC) programming language for stepping instructions and sequence control.
20. The meaning of the interrupt symbol I001 is: when the input X0 is from OFF-NO, the interrupt service subroutine with the index as the label is executed and returned according to the (IRET instruction).
21. The minimum I/O response time of the PLC is: the filtering time of one scan cycle T+ input and output.
22. PLC control system load changes frequently and large, application (thyristor) output form of PLC.
23. In the state transition diagram programming, the state transition is available (OUT) when the branch program needs to repeat or jump during execution.
24. In the program design, the available devices and their address numbers are incorrect in the function instructions, and the instruction execution (M8067) is set. The error step address is stored in (D8069).
25. The topology of the LAN is divided into geometric maps (bus type), (ring), and (star).
26. Serial data communication working mode (simplex communication), (half duplex communication), (full duplex communication).
27. Star Delta Buck Start is only used for motors where the stator windings are connected (triangle) during normal operation.
28. The working principle of the programmable controller adopts (circular scanning, centralized input and output) special working mode, and the hardware design adopts (modular) structure.
29. PLC memory is mainly divided into (EPROM), (RAM), (EEPROM) according to different requirements of read and write operations.
30. The input and output relays of the PLC (input) relays are only driven by external signals, and the (output) relays are only driven by the program.
31. There are 21 internal signal high-speed counters in the PLC, and the counting signals are input from the input ports (X0~X5). The PLC provides (9) interrupt points and (3) interrupt instructions.
32. PLC does not set a special analog I/O image, and the input amount after A/D conversion is stored in (buffer data register in A/D module).
33. The PLC network master station and slave station are connected by a communication cable, and the slave station and the slave station are connected by a (RS-232CRS-422A) communication cable.
34. The return coefficient of an electromagnetic voltage relay is defined as the ratio of (release voltage) to (push-in voltage).
35. The host of the PLC is (central processing unit CPU), (memory), (input and output unit), (power supply unit).
36. The function of the auxiliary relay in the programming software of PLC is equivalent to the function of the (intermediate relay) timer in the relay control system, which is equivalent to the (time relay) in the relay control system.
37. The timing resolution of the timer T225 of the PLC is (10ms). Use it to achieve a timing delay of 10s, the set value is (1000).
38. When the special auxiliary relay is turned on (set to 1), it is counted (decreasing).
39. The microcomputer working mode adopts (interrupt processing) PLC adoption (cyclic scanning, centralized input and centralized output).
40. The intermediate relay is mainly used to expand the other relays (number of contacts and capacity) to function as a signal relay.
41. The IEC specifies that programmable controllers and their associated peripherals are designed for the reason that (industrial) systems are integrated to easily expand their functionality.
42. PLC control system generally consists of (basic unit), I/O expansion module and expansion unit, I/O special function module and programmer and other peripheral devices.
43. In the programming software of PLC, the input and output relays have a total of (256) points, and all adopt (8) coding.
44. In the PLC, the OUT command cannot be used for the (input) relay.
45. The character frame format of the asynchronous communication method uses (start bit) to indicate the start of a character, and (stop bit) to indicate the end of a character.
46. ​​PLC does not set a special analog I/O image, and it can expand (analog A/D conversion input FX-4AD) special function I/O module for analog input.
47. Electrical control system diagram (electrical schematic), (electrical component layout), (electrical installation wiring diagram).
48. The (modular) structure of the PLC will form the individual parts of the PLC into separate modules and be mounted to the same base plate or frame.
49. PLC's basic unit FX2-24MR output mode is (relay output) The maximum number of I/O points of the expansion module is (16).
50. The timing resolution of the timer T240 in the PLC is (10ms). If the fixed time is 1s, the set value K is (100).
51. PLC in the I / O information processing process, the input image register each switch state and data depends on the state of each input port (in the input sampling phase) and the acquisition data.
52. The main control command of PLC is (MC), and the normally closed contact connected to the lower end of the main control contact should use (LDI) command.
53. The PLC program processes the allowable interrupt interval. When (X2) is OFF to ON, the interrupt service subroutine with the interrupt pointer number I201 is processed instead.
54. The LAN architecture includes (transmission media), (transport technology), (network topology), and (access extension method).
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