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CJ/T 188-2018 English PDF (CJT188-2018)

CJ/T 188-2018 English PDF (CJT188-2018)

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CJ/T 188-2018: Technical requirements of utility meters data transmission

This standard specifies the functional requirements, physical layer, data link layer, data security, application layer for data transmission of household metering instruments (hereinafter referred to as meters). This standard is applicable to the automatic reading system, for data exchange between the master station and the slave station, one master and one slave, or one master and multiple slaves.
CJ/T 188-2018
URBAN-RURAL CONSTRUCTION INDUSTRY STANDARD
OF THE PEOPLE REPUBLIC OF CHINA
ICS 35.240.99
L 78
Replacing CJ/T 188-2004
Technical requirements of utility meters data transmission
ISSUED ON: MARCH 08, 2018
IMPLEMENTED ON: OCTOBER 01, 2018
Issued by: Ministry of Housing and Urban-Rural Development of PRC
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions... 6
4 Functional requirements ... 7
5 Physical layer... 10
6 Data-link layer ... 10
7 Data security ... 15
8 Application layer ... 17
Technical requirements of utility meters data transmission
1 Scope
This standard specifies the functional requirements, physical layer, data link layer, data security, application layer for data transmission of household metering instruments (hereinafter referred to as meters).
This standard is applicable to the automatic reading system, for data exchange between the master station and the slave station, one master and one slave, or one master and multiple slaves.
2 Normative references
The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) is applicable to this standard.
GB/T 778.1 Measurement of water flow in fully charged closed conduits - Meters for cold potable water and hot water - Part 1: Specifications
GB/T 6968 Diaphragm gas meters
GB/T 19582.1 Modbus industrial automation network specification - Part 1: Modbus application protocol
GB/T 19897.1-2005 Automatic meter reading system lower layer communication protocol - Part 1: direct local data exchange
GB/T 26831.2 Society energy metering for reading system specification - Part 2: Physical and link layer
GB/T 26831.3-2012 Society energy metering for reading system specification - Part 3: Dedicated application layer
GB/T 32224 Heat meters
GM/T 0002-2012 SM4 Block cipher algorithm
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Automatic meter reading system
The system, by which the data of multiple slave stations is read automatically by the master station, through the physical channel, referred to as the automatic meter reading (AMR).
3.2
Master station
A device that selects one, a group or all of the slave stations AND initiates an information exchange with the slave stations. It can be a concentrator, a handheld device, a computer, or other data terminal.
3.3
Slave station
A device, that has a unique identification address in the entire network, receives information from the master station, exchanges information with the master station. Note: In this standard, it refers to instrument.
3.4
Bus
A physical cline, that connects the master station with multiple slave stations. 3.5
Physical layer
It specifies the physical interface between the master station and the slave station, as well as the physical and electrical characteristics of the interface. It is responsible for the reception and transmission of information, on the physical medium. 3.6
Data-link layer
It specifies the composition of the information exchange frame, between the master station and the slave station, the flow control of the information exchange, the network protocol layer of error control.
3.7
Hand-held unit
Portable device that can exchange data with the slave station.
4 Functional requirements
4.1 General requirements
4.1.1 The automatic meter reading system shall have the ability to identify different types of slave stations and two-way communication.
4.1.2 The slave station shall have a communication interface. The interface shall comply with the provisions of Chapter 5 of this standard.
4.1.3 The automatic meter reading system shall be able to collect battery voltage status, valve status (only for slave stations, which have valve control function), etc. 4.1.4 The schematic diagram of the composition of the automatic meter reading system is as shown in Figure 1.
4.5.6 The output parameters of the heat (cold) meter shall include real-time time, heating (cooling) volume on settlement day, current heating (cooling) volume, thermal power, instantaneous flow, cumulative flow, water supply temperature, return water temperature, cumulative working time, etc.
5 Physical layer
5.1 Interface form
Instrument communication interfaces include M-Bus interface, RS-485 interface, wireless transceiver interface, optical interface. When using other interfaces, it shall comply with the provisions of relevant standards.
5.2 M-Bus interface
The M-Bus interface shall comply with the relevant provisions of GB/T 26831.2. 5.3 RS-485 interface
The RS-485 interface shall comply with the relevant provisions of GB/T 19582.1. 5.4 Wireless transceiver interface
The radio frequency, which is used by the wireless transceiver interface, is preferably the 433 MHz frequency band, the 470MHz frequency band, the 780 MHz frequency band or the 868 MHz frequency band. Transmission power and other main technical indicators shall comply with relevant national requirements.
5.5 Optical interface
5.5.1 The optical interface can be a contact optical interface or an open optical interface. 5.5.2 The contact optical interface shall comply with the provisions of "4.3 Optical interface" in GB/T 19897.1-2005.
5.5.3 The open optical interface shall comply with the provisions of "Appendix F Open optical interface" in GB/T 19897.1-2005.
6 Data-link layer
6.1 Protocol communication method
This protocol adopts the half-duplex communication mode of master-slave structure. 6.2 Byte format
6.3.6 The data field (DATA) includes data identification, serial number, data; its structure changes with the function of the control code.
6.3.7 The check code (CS) is one byte; all bytes, from the frame start character (including the frame start character) to the check code, are accumulated in binary arithmetic, excluding the overflow value which exceeds FFH.
6.4 Transmission requirements
6.4.1 Preamble byte: When using wired interface, 2 bytes ~ 4 bytes FEH shall be sent, before sending frame information.
6.4.2 Transmission order: All multi-byte data fields transmit the low-order byte first, followed by the high-order byte.
6.4.3 Transmission response: The master station sends out a command frame for each communication; the selected slave station responds according to the requirements of the command frame. The timing of the transmission response is as shown in Figure 4, Figure 5, Figure 6.
Binary bit transfer time Tbit = 1/Baud rate (s);
Byte transfer time Tbyte = 11 Tbit;
Delay time Td = 1 Tbyte;
Frame transmission time Tframe = Number of frame bytes ?? (Tbyte + Tb);
The longest response time Tr = 500 ms + 30 ?? Tbyte;
Line idle time Tli = 30 ms;
Actual frame transmission time Tfba = Actual frame byte length ?? (Tbyte + Tb); Pause time between bytes Tb ??? 1 Tbyte;
The number of repeated communications I ??? 3.
7.3 Key management
The 16-byte key is defined and managed by the vendor and the user. The key management shall be secure and reliable.
7.4 Data padding
7.4.1 The plaintext data area to be encrypted is the part of the data field (DATA), after removing the data identification DI and the serial number SER. Before data encryption, data padding shall be performed first.
7.4.2 Pad the current timestamp of 6 bytes, before the plaintext data area to be encrypted. The timestamp is the BCD code of YYMMDDhhmmss; YY is the last two digits of the year. See Table 5 for the format.
7.4.3 Perform padding, according to PKCS7, after the plaintext data area to be encrypted. If the length of the plaintext data area, which contains the timestamp, is an integer multiple of 16 bytes, pad with 10H of 16 bytes; if N (0H < N < 10H) bytes need to be supplemented to achieve an integer multiple, pad with the value N of N bytes. 7.5 Data encryption
7.5.1 The padded data is encrypted according to the SM4 encryption algorithm. After the encryption is completed, replace the content of the data field of the frame; modify the data length field and check code to the correct value.
7.5.2 Both the request frame, which is sent by the master station, AND the normal response frame from the slave station, can be transmitted in cipher text. Only the master station can initiate ciphertext transmission. When the master station does not initiate a ciphertext transmission request, the slave station cannot actively reply to encrypted data. 7.5.3 When the master station requests frame control code D3 bit to 1, AND a ciphertext transmission request is initiated, the control code D3 bit must also be set to 1, no matter whether the normal response frame of slave station carries encrypted data; if the slave station does not support ciphertext response, it shall send an abnormal response frame. 7.5.4 The abnormal response frame of the slave station shall be transmitted in plain text. No matter how the D3 bit of the master station?€?s request frame control code is set, the D3 bit of the control code of the abnormal response frame of the slave station must be 0, to ensure the compatibility with the earlier instruments, that do not support encryption.

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