CJ/T 188-2018Technical requirements of utility meters data transmission (English PDF)

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.

4.2 Function of master station

4.2.1 It shall be able to automatically read and receive the data of each slave station, according to the set time; have the functions of real-time random reading and selective reading by address.

4.2.2 It shall be able to set the initial parameters of the master station, such as time, etc.;

there shall be measures to prevent unauthorized personnel from operating.

4.2.3 It shall be able to realize the time calibration of the slave station system.

4.3 Function of slave station

4.3.1 It shall be able to receive and respond to the master station’s reading information.

4.4 Data transmission reliability

4.4.1 The one-time reading success rate is calculated, according to formula (1).

4.5 Meters

4.5.1 The accuracy of the water meter shall comply with the relevant provisions of

GB/T 778.1.

4.5.2 The output parameters of the water meter shall include the current cumulative

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.

5.1 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.

5.4 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

6.1 Protocol communication method

This protocol adopts the half-duplex communication mode of master-slave structure.

6.3 Frame format

6.3.1 The frame format shall comply with the provisions of Table 2.

6.3.4 The format of the control code (C) is as shown in Figure 3.

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.

6.4.4 Error control. If the receiver detects a checksum, even check bit or format error, it shall abandon the information frame and not respond.

6.4.5 Transmission rate. The commonly used rates are 300 bps, 600 bps, 1200 bps, 2400 bps, 4800 bps, 9600 bps.

7.1 Security requirements

It shall comply with the relevant provisions of the national password management.

7.2 Cryptographic algorithms

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.

7.5 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.

7.6 Data decryption

7.6.1 After receiving the data, the decryption operation shall be performed, according to the SM4 cipher algorithm, which is specified in GM/T 0002-2012.

7.6.2 After the data decryption is completed, the padding content is removed, the original data is restored for data processing.

8.1 Read operation

8.1.4 The function of the slave station’s abnormal response frame is that the slave station receives the response of the error control code.

8.2 Write operation

8.2.1 During write operation, the serial number SER, which is sent by the master station, is incremented by 1 (modulo 256), before each communication. The response serial number of the slave station shall be the same as the serial number, which is sent by the master station.

8.2.3 The function of the normal response frame of the slave station is to inform the master station of the execution result of the request command.

8.2.5 The coding format of the master station’s request for write operation shall comply with the provisions of Table 15.

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