CN105278918A

CN105278918A - Reading method of register and register using reading method

Info

Publication number: CN105278918A
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: 2016-01-27
Anticipated expiration: 2035-10-15
Also published as: CN105278918B

Abstract

The invention discloses a reading method of a register and the register using the reading method, wherein the reading method comprises the following steps of (1) calculating the total communication time Tsum1 of a primary request respond in a non-segmented reading mode; (2) calculating the total communication time Tsum2 of the primary request respond in a segmented reading mode; and (3) comparing the Tsum1 and the Tsum2, and determining whether to use the non-segmented mode or the segmented reading mode according to the number value of vacant addresses. The reading method related by the invention can help people to judge whether to use the segmented reading or non-segmented reading mode in the Modbus-RTU communication, so that the proper reading mode is preferentially selected; and the communication efficiency during the register reading is effectively improved.

Description

The read method of register and the register of this read method of employing

Technical field

The present invention relates to digital independent field, be specifically related to a kind of read method of register; The invention still further relates to a kind of register, be specifically related to a kind of discontinuous address space holding register adopting this read method.

Background technology

In Modbus communications protocol content; due to reserved or other reason; from the input register of machine or the address space of holding register discontinuous often; vacant a part of address of frequent meeting intermittent in address space; like this when host computer is to monitoring in real time from machine and constantly reading its running status in bus, the data reading mode for discontinuous address space just becomes the key affecting its communication efficiency.Traditional reading manner for discontinuous address space register mainly comprises the following two kinds mode: mode one, not segmentation is read, namely once read all the elements from lowest address to maximum address, comprise and reserving or the content of vacant intermediate address due to other reason, and only resolve significant part in institute's reading of content; Mode two, segmentation is read, and namely reads the data content of each contiguous segmentation part in discontinuous address space respectively one by one.

Consider slave addresses in reading order, function code, start address, register length, the impact of the factors such as check byte, when the vacant scope of address narrow (between as two significant addresses only a vacant address), mode one can improve communication efficiency relative to mode two, but when the vacant scope in address is wider (between as two significant address segmentations vacant 100 addresses), although mode two needs twi-read, but the communication time produced (comprises the time shared by Twice requests frame, time shared by twice response frame, dead times before dead times and two responses before two requests) be often less than the communication time (time shared by a claim frame that mode one produces, time shared by a response frame, dead time before a request, dead time before a response).In sum, these two kinds of modes, are applicable to the vacant situation in different addresses respectively, therefore need the vacant situation according to address space and in conjunction with concrete communication process parameter optimum selecting reading manner.

Summary of the invention

A kind of read method of register is provided in the embodiment of the present invention and adopts the register of this read method, to solve the problem that cannot effectively read when the address space of register occurs vacant in prior art.

For achieving the above object, the invention provides a kind of read method of register, it comprises the following steps: 1) calculate the total communication time Tsum1 once asking to respond taking not segmentation reading manner; 2) the total communication time Tsum2 once asking to respond taking segmentation reading manner is calculated; 3) compare Tsum1 and Tsum2, determine to adopt not segmentation reading manner or segmentation reading manner according to the individual numerical value of idle address.

As preferably, the total communication time responded once is asked to comprise the front dead time T1 of request, response front dead time T2, claim frame holding time and response frame holding time.

As preferably, as e1> (Br/16) (104/Br+T1+T2), select segmentation reading manner, wherein, e1 is vacant address number, and Br is the baud rate of serial communication.

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

As preferably, the communication T.T. responded of once asking of not segmentation reading manner is: Tsum1=(16/Br) * (n1+e1+n2)+(104/Br+T1+T2), wherein, n1 and n2 is the number of two sections of effective addresses.

As preferably, the communication T.T. responded of once asking of segmentation reading manner is: Tsum2=(16/Br) * n1+ (104/Br+T1+T2)+(16/Br) * n2+ (104/Br+T1+T2).

As preferably, ask front dead time T1 to be determined by upper machine communication main frame, the front dead time T2 of response is determined from machine by slave computer communication.

The present invention also provides discontinuous address space holding register in a kind of Modbus-RTU communication, and it adopts the read method in technique scheme.

The read method that the present invention relates to can help to judge to adopt segmentation to read still not segmentation reading manner in Modbus-RTU communication, thus the reading manner that optimum selecting is suitable, effectively improve communication efficiency when reading register.

Accompanying drawing explanation

Fig. 1 is the communication T.T. schematic diagram asking in the read method that the present invention relates to respond;

Fig. 2 is with vacant Modbus communication protocol address configuration schematic diagram in the read method that the present invention relates to.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail, but not as a limitation of the invention.

Fig. 1 shows in communication the communication time schematic diagram of asking response, as can be seen from Figure 1 once asks the time responded to comprise request front dead time, claim frame holding time, response front dead time, response frame holding time.Therefore, when calculating the communication T.T. of once asking to respond, first the baud rate of communication of setting up serial ports is Br, before front dead time and response are asked in setting simultaneously, the dead time is set to T1 and T2 respectively, setting claim frame holding time is Trequest, response frame holding time is Tresponse, then once ask the communication T.T. responded to be Tsum, it is expressed as follows:

Tsum＝T1+T2+Trequest+Tresponse。

Under Modbus-RTU communication mode, 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 the frame format of claim frame, response frame is respectively as shown in table 1, table 2:

Table 1 claim frame form

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

Table 2 response frame form

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 once ask respond communication T.T. be:

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

General in the communication of specifically monitored system, the baud rate Br of serial communication is fixing, before request, dead time T1 can be determined by host computer (host computer communication), before response, dead time T2 is determined by slave computer (communication is from machine), this shows, once ask the address number n of communication T.T. and the read access responded linear.

Fig. 2 shows the vacant Modbus communication protocol address configuration of band, and wherein, the number of two sections of effective addresses is respectively n1 and n2, and address number vacant is therebetween e1.The embodiment of the present invention can according to the vacant situation of address space, consider the baud rate of serial communication simultaneously and ask the front dead time and the dead time before responding, by comparing communication T.T., preferentially make a choice in not segmentation reading manner and segmentation reading manner.

When reading the register of non-address continuous space under Modbus communications protocol, namely occurring that the communication T.T. account form in specific vacant situation is as follows:

Take not segmentation reading manner once ask respond communication T.T. be:

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

Take segmentation reading manner once ask respond communication T.T. be:

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

By above-mentioned formula, we adopt not segmentation reading manner and segmentation reading manner in the difference on T.T. that communicates under can judging to occur specific vacant situation.By comparing Tsum1 and Tsum2, calculate when Tsum1>Tsum2 (namely segmentation reading manner is better than not segmentation reading manner), namely, time e1> (Br/16) (104/Br+T1+T2), the communication T.T. of not segmentation reading manner relatively communication T.T. of segmentation reading manner is shorter.

Therefore, for the specific communication adopting Modbus/RTU pattern, when before baud rate Br, request, dead time T1 and the front dead time T2 of response is fixing (generally, these parameters are all fixing), the number of idle address is when being greater than (Br/16) (104/Br+T1+T2), select segmentation reading manner to read register, otherwise adopt not segmentation reading manner to read register.

Embodiments of the invention are only the descriptions carried out the preferred embodiment of the present invention; not design of the present invention and scope are limited; under the prerequisite not departing from design philosophy of the present invention; the various modification that in this area, engineering technical personnel make technical scheme of the present invention and improvement; protection scope of the present invention all should be fallen into; the technology contents of request protection of the present invention, all records in detail in the claims.

Claims

1. a read method for register, is characterized in that, comprises the following steps: 1) calculate the total communication time Tsum1 once asking to respond taking not segmentation reading manner; 2) the total communication time Tsum2 once asking to respond taking segmentation reading manner is calculated; 3) more described Tsum1 and described Tsum2, determines not segmentation reading manner or described segmentation reading manner described in employing according to the individual numerical value of idle address.

2. read method according to claim 1, is characterized in that, the described total communication time responded of once asking comprises the front dead time T1 of request, response front dead time T2, claim frame holding time and response frame holding time.

3. read method according to claim 2, is characterized in that, as e1> (Br/16) (104/Br+T1+T2), select described segmentation reading manner, wherein, e1 is vacant address number, and Br is the baud rate of serial communication.

4. read method according to claim 3, is characterized in that, under Modbus-RTU communication mode, the claim frame of read input register and holding register is fixed as 8 bytes, response frame is 5+2*n byte, and wherein, n is expressed as the address number once read.

5. read method according to claim 4, it is characterized in that, the communication T.T. responded of once asking of described not segmentation reading manner is: Tsum1=(16/Br) * (n1+e1+n2)+(104/Br+T1+T2), wherein, n1 and n2 is the number of two sections of effective addresses.

6. read method according to claim 5, it is characterized in that, the communication T.T. responded of once asking of described segmentation reading manner is: Tsum2=(16/Br) * n1+ (104/Br+T1+T2)+(16/Br) * n2+ (104/Br+T1+T2).

7. the read method any one of claim 1-6 described in claim, is characterized in that, before described request, dead time T1 is determined by upper machine communication main frame, and before described response, dead time T2 is determined from machine by slave computer communication.

8. a discontinuous address space holding register in Modbus-RTU communication, is characterized in that, have employed the read method described in above-mentioned any one claim.