CN105278918B

CN105278918B - The read method of register and the register using the read method

Info

Publication number: CN105278918B
Application number: CN201510673664.9A
Authority: CN
Inventors: 张宜宁; 刘继; 马丽; 邵世卓; 王灵军; 唐友志; 宋海川
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2015-10-15
Filing date: 2015-10-15
Publication date: 2017-12-08
Anticipated expiration: 2035-10-15
Also published as: CN105278918A

Abstract

The present invention discloses a kind of read method of register and the register using this method, and wherein read method comprises the following steps：1) calculate and take the total communication time Tsum1 for once asking response for not being segmented reading manner；2) the total communication time Tsum2 for once asking response for taking segmentation reading manner is calculated；3) compare Tsum1 and Tsum2, used according to the determination of the individual numerical value of idle address and be not segmented reading manner or segmentation reading manner.Read method of the present invention can help to judge to read using segmentation in Modbus RTU are communicated still not to be segmented reading manner, so as to the suitable reading manner of optimum selecting, effectively improve communication efficiency when reading register.

Description

The read method of register and the register using the read method

Technical field

The present invention relates to digital independent field, and in particular to a kind of read method of register；The invention further relates to one kind A kind of register, and in particular to discontinuous address space holding register using the read method.

Background technology

In Modbus communications protocol contents, due to reserved or other reasons, the input register or holding register of slave Address space it is often discontinuous, often vacant a part of address of intermittent in address space, so work as host computer When being monitored in real time to the slave in bus and constantly reading its running status, for the digital independent of discontinuous address space Mode just turns into the key for influenceing its communication efficiency.Traditional reading manner for discontinuous address space register mainly wraps Include the following two kinds mode：Mode one, reading is not segmented, that is, once read all interior from lowest address to maximum address Hold, including the reserved or content of vacant intermediate address due to other reasons, and only parse significant in institute's reading of content Part；Mode two, segmentation is read, that is, is read one by one respectively in discontinuous address space in the data of each contiguous segmentation part Hold.

In view of the factor such as slave addresses, function code, initial address, register capacity, check byte in reading order Influence, during vacant scope narrow (between such as two significant addresses an only vacant address) in address, the phase of mode one Communication efficiency can be improved for mode two, but when the vacant scope in address is wider (between such as two significant address segmentations Vacant 100 addresses), although mode two needs twi-read, caused communication time (including shared by Twice requests frame Time, twice the time shared by response frame, two request before the dead time and two response before the dead time) it is often small In communication time caused by mode one (time shared by time, a response frame shared by a claim frame, one please Ask the preceding dead time, one response before the dead time).In summary, both modes, it is vacant to be respectively suitable for different addresses Situation, it is therefore desirable to according to the vacant situation of address space and combine specific communication process parameter optimum selecting reading manner.

The content of the invention

A kind of read method of register and the register using the read method are provided in the embodiment of the present invention, to solve The problem of can not effectively being read when the address space of register occurs vacant in the prior art.

To achieve the above object, the present invention provides a kind of read method of register, and it comprises the following steps：1) calculate and adopt Take the total communication time Tsum1 for once asking response for not being segmented reading manner；2) calculate and take segmentation reading manner once Ask total communication time Tsum2 of response；3) compare Tsum1 and Tsum2, according to the individual numerical value of idle address determine using regardless of Section reading manner or segmentation reading manner.

Preferably, total communication time of response is once asked to include dead time T1 before asking, dead time before response T2, claim frame holding time and response frame holding time.

Preferably, work as e1>(Br/16) when (104/Br+T1+T2), selection segmentation reading manner, wherein, e1 is vacant Address number, Br be serial communication baud rate.

Preferably, under Modbus-RTU communication modes, the claim frame of read input register and holding register is fixed For 8 bytes, response frame is 5+2*n byte, wherein, n is expressed as the address number once read.

Preferably, the communication total time for once asking response for not being segmented reading manner is：Tsum1=(16/Br) * (n1+e1+n2)+(104/Br+T1+T2), wherein, n1 and the number that n2 is two sections of effective addresses.

Preferably, the communication total time for once asking response of segmentation reading manner is：Tsum2=(16/Br) * n1+ (104/Br+T1+T2)+(16/Br)*n2+(104/Br+T1+T2)。

Preferably, dead time T1 is determined that the dead time, T2 was by bottom before response by upper machine communication main frame before request Machine communication slave determines.

The present invention also provides discontinuous address space holding register in a kind of Modbus-RTU communications, and it uses above-mentioned skill Read method in art scheme.

Read method of the present invention can help to judge to read still not using segmentation in Modbus-RTU communications Reading manner is segmented, so as to the suitable reading manner of optimum selecting, effectively improves communication efficiency when reading register.

Brief description of the drawings

Fig. 1 is the communication total time schematic diagram that response is asked in read method of the present invention；

Fig. 2 is with vacant Modbus communication protocol address configuration schematic diagrams in read method of the present invention.

Embodiment

The present invention is described in further detail with specific embodiment below in conjunction with the accompanying drawings, but not as the limit to the present invention It is fixed.

Fig. 1 shows the communication time schematic diagram that response is asked in communication, as can be seen from Figure 1 once asks response Time includes before asking dead time, response frame holding time before dead time, claim frame holding time, response.Therefore, counting When calculating the communication total time for once asking response, the baud rate for communication of setting up serial ports first is Br, is paused before concurrently setting request The dead time is set to T1 and T2 before time and response, sets claim frame holding time as Trequest, when response frame takes Between be Tresponse, then once ask response communication total time be Tsum, its expression is as follows：

Tsum=T1+T2+Trequest+Tresponse.

Under Modbus-RTU communication modes, the claim frame of read input register and holding register is fixed as 8 bytes, Response frame is 5+2*n byte (n is expressed as the address number once read), and claim frame, the frame format of response frame are respectively such as table 1st, shown in table 2：

Table 1 asks frame format

Device address	Function code	Initial address	Data bulk	CRC check code
					1 Byte	1 Byte	2 Bytes	2 Bytes	2 Bytes

The response frame form of table 2

Device address	Function code	Byte number	Valid data	CRC check code
					1 Byte	1 Byte	1 Byte	n Bytes	2 Bytes

Then：

Claim frame holding time Trequest=(8/Br) * 8

Response frame holding time Trequest=(8/Br) * (5+2*n)

So the communication total time for once asking response is：

Tsum=T1+T2+Trequest+Tresponse=(16/Br) * n+ (104/Br+T1+T2)

Typically in the communication of specifically monitored system, the baud rate Br of serial communication is fixed, the dead time before request T1 can be determined that dead time T2 is determined by slave computer (communication slave) before response by host computer (host computer communication), it is possible thereby to Find out, once the communication total time of request response and the address number n of read access are linear.

Fig. 2 is shown to be configured with vacant Modbus communication protocol addresses, wherein, the number difference of two sections of effective addresses For n1 and n2, vacant address number is e1 therebetween.The embodiment of the present invention can be examined simultaneously according to the vacant situation of address space Consider serial communication baud rate and request before the dead time and response before the dead time, by compare communication total time, not Preferentially made a choice in segmentation reading manner and segmentation reading manner.

When the register of non-address continuous space is read under Modbus communications protocol, that is, there are specific vacant feelings Communication total time calculation under condition is as follows：

Take be not segmented reading manner once ask response communication total time be：

Tsum1=(16/Br) * (n1+e1+n2)+(104/Br+T1+T2)

Take segmentation reading manner once ask response communication total time be：

Tsum2=(16/Br) * n1+ (104/Br+T1+T2)+(16/Br) * n2+ (104/Br+T1+T2)

By above-mentioned formula, we may determine that occur it is specific it is vacant in the case of using not being segmented reading manner and segmentation is read Take difference of the mode on communication total time.By comparing Tsum1 and Tsum2, calculate and work as Tsum1>Tsum2 (i.e. read by segmentation Mode is taken to be better than not being segmented reading manner) when, i.e. e1>(Br/16) when (104/Br+T1+T2), the communication for being segmented reading manner is total The communication total time that time is not segmented reading manner relatively is shorter.

Therefore, for the specific communication for using Modbus/RTU patterns, dead time T1 and sound before baud rate Br, request In the case of should fixing preceding dead time T2 (generally, these parameters are all fixed), the number of idle address exists In the case of (Br/16) (104/Br+T1+T2), selection segmentation reading manner reads register, otherwise uses and is not segmented reading Mode is taken to read register.

Embodiments of the invention are only the descriptions carried out to the preferred embodiment of the present invention, not to present inventive concept and Scope is defined, on the premise of design philosophy of the present invention is not departed from, skill of the engineers and technicians to the present invention in this area The all variations and modifications that art scheme is made, all should fall into protection scope of the present invention, the claimed technology contents of the present invention, All record in detail in the claims.

Claims

1. a kind of read method of register, it is characterised in that comprise the following steps：1) calculate to take and be not segmented reading manner Once ask total communication time Tsum1 of response；2) calculate and take when once asking total communication of response of segmentation reading manner Between Tsum2；3) the Tsum1 and Tsum2, reading is not segmented according to the individual numerical value of idle address determines use Mode or the segmentation reading manner, described be not segmented are read as once reading in all from lowest address to maximum address Hold, only parse part significant in institute's reading of content；The segmentation is read as reading one by one in discontinuous address space respectively The data content of each contiguous segmentation part；

Wherein, under Modbus-RTU communication modes, the claim frame of read input register and holding register is fixed as 8 words Section, response frame is 5+2*n byte, and n is expressed as the address number once read；The once request for not being segmented reading manner The communication total time of response is：Tsum1=(16/Br) * (n1+e1+n2)+(104/Br+T1+T2), the segmentation reading manner Once ask response communication total time be：Tsum2=(16/Br) * n1+ (104/Br+T1+T2)+(16/Br) * n2+ (104/Br+T1+T2), n1 and n2 are the number of two sections of effective addresses；

It is described once to ask total communication time of response to include dead time T1 before asking, dead time T2, claim frame before response Holding time and response frame holding time；

Work as e1>(Br/16) when (104/Br+T1+T2), the segmentation reading manner is selected, wherein, e1 is vacant address Number, Br are the baud rate of serial communication.

2. read method according to claim 1, it is characterised in that the dead time, T1 was by upper machine communication before the request Main frame determines that dead time T2 is determined by slave computer communication slave before the response.

3. discontinuous address space holding register in a kind of Modbus-RTU communications, it is characterised in that employ any of the above-described Read method described in item claim.