Data transmission standard for online monitoring systems of pollutant
1 Scope
This standard is applicable to the data transmission between the online monitoring systems of pollutant, the automatic monitoring system of pollutant discharge process and the monitoring center. It specifies the transmission process and the formats of parameter commands, interactive commands, data commands and control commands, and describes the code definitions. This standard allows extension, provided that the extension shall not conflict with the control commands used or kept in this standard.
It also specifies the format of data transmission between online monitoring instrumentation and data collection and transmission equipment, and describes the code definition.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For undated references, the latest edition applies.
GB 3096-2008 Environmental quality standards for noise
GB/T 16706-1996 Codes for environmental pollution source categories
GB/T 19582-2008 Modbus industrial automation network specification
HJ/T 75-2007 Specifications for continuous emissions monitoring of flue gas emitted from stationary sources (on trial)
HJ/T 76-2007 Specification and test procedures for continuous emission monitoring systems of flue gas emitted from stationary sources (on trial)
HJ 524-2009 Codes for air pollutants
HJ 525-2009 Codes for water pollutants
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1 online monitoring systems of pollutant
system consisting of online monitoring instrumentation of pollutant, data collection and transmission equipment, automatic monitoring equipment for pollutant discharge process and monitoring center
3.2 monitoring center
data receiving and processing system installed in environmental protection departments at all levels, which is connected with automatic monitoring equipment through transport network to send out instructions such as inquiry and control, including computers and computer software, etc. It is referred to as upper computer for short.
3.3 online monitoring equipment
equipment installed at pollutant monitoring points and process nodes affecting pollutant discharge, which is used to monitor pollutant discharge condition and process parameters and complete communication and transmission with upper computer, including pollutant monitoring instrumentation, flowmeter, operation recorder for pollution treatment equipment, data collection and transmission equipment, etc. It is referred to as on-site computer for short.
3.4 data collection and transmission equipment
equipment for collecting data of various types of monitoring instrumentation, and completing data storage and data transmission and communication with upper computer, including single-chip microcomputer, industrial personal computer, embedded computer, Programmable Automation Controller (PAC) or Programmable Logic Controller (PLC), etc.
3.5 pollution treatment equipment
equipment and devices for pollutant treatment, collectively referred to as pollution treatment equipment
3.6 process monitoring
monitoring, in line with the process design, the key operation parameters (including process parameters such as flow rate, temperature, oxygen content and pressure, and electrical parameters such as current, voltage, frequency and rotational speed) of production facilities and pollution treatment equipment (hereinafter referred to as treatment equipment) that affect pollutant discharge; comprehensively monitoring, in combination with the production process and terminal monitoring data of the enterprise, the operation of the production facilities and treatment equipment of the enterprise, and the pollutant treatment effect and discharge situation, and judging the rationality, authenticity and acceptability of the pollutant discharge monitoring data
3.7 clearance
cleaning and rinsing, prior to testing samples with online monitoring equipment, injection pipeline and main measurement components with clear water, water samples, chemicals, etc. to ensure the accuracy of measurement data
3.8 blowback
regular and automatic blowing of measurement circuit with high-pressure gas for the smoothness of the circuit, in order to prevent the blockage or obstruction of the measurement circuit from affecting the measurement results during the measurement process of online monitoring instrumentation
3.9 sampling for overproof
process of automatic sampling equipment to collect pollutant samples triggered when the pollutant discharge is out of limits
3.10 zero calibration
indicated value of the online monitoring instrumentation calibrated to zero when the zero calibration fluid is used as the specimen for testing
3.11 sampling cycle
time interval between two adjacent sampling operations for discontinuous online monitoring instrumentation
3.12 comparison sampling
testing by online monitoring instrumentation with standard samples as specimens, to verify the accuracy of monitoring results of online monitoring instrumentation
3.13 range calibration
testing with range calibration fluid (or standard gas sample) as specimen, to calibrate the indicated value of instrument to the range value, relative to the measuring range of online monitoring instrumentation
3.14 immediate sampling
immediate sampling test by online monitoring instrumentation under the instructions from the upper computer, for discontinuous online monitoring instrumentation
3.15 sampling time
duration from sampling to output of measurement results, for discontinuous online monitoring instrumentation
4 System architecture
The online monitoring systems of pollutant can be divided into three levels from bottom to top: on-site computer, transport network and upper computer. The upper computercommunicates (including initiation, data exchange, response, etc.) with the on-site computer through the transport network.
The online monitoring systems of pollutant has two kinds of constitution:
1) One set of on-site computer, integrating automatic monitoring, storage and communication transmission functions, directly interacts with the upper computer through the transport network, as shown in Figure 1.
Figure 1 System constitution 1
2) There are one or more sets of monitoring instrumentation on site that have digital output interfaces and are connected to independent data collection and transmission equipment. The upper computer communicates with the data collection and transmission equipment through transport network (including initiation, data exchange, response, etc.), as shown in Figure 2.
Figure 2 System constitution 2
5 Protocol hierarchy
The communication interface between the on-site computer and the upper computer shall meet the requirements of the selected transport network, which is not specified in this standard.
The data transmission protocol specified in this standard corresponds to the application layer of the protocol model defined by ISO/OSI, and provides interactive communication between the on-site computer and the upper computer based on different transport networks.
The protocol structure is shown in Figure 3.
Figure 3 Data transmission and communication protocol structure
For the purpose of this standard, the underlying transport layer is built on the TCP/IP protocol that is applicable to the following communication media:
GPRS General Packet Radio Service
ADSL Asymmetrical Digital Subscriber Loop
CDMA Code Division Multiple Access
WCDMA Wideband CDMA
TD-SCDMA Time Division - Synchronous CDMA
CDMA2000 Code Division Multiple Access 2000
PLC Power Line Communication
TD-LTE Time Division Long Term Evolution
FDD-LTE Frequency Division Duplex Long Term Evolution
WiMAX Worldwide Interoperability for Microwave Access
The above-mentioned one or more communication media constitute the transport network referred to in this standard.
In this standard, the application layer relies on the underlying transport layer that adopts TCP/IP protocol (it has four layers, i.e. network interface layer, network layer, transport layer, application layer). TCP/IP protocol is constructed on the selected transport network, and the network interface layer of TCP/IP protocol realizes the interface with the transport network. The application layer replaces the application layer of TCP/IP protocol (only three layers are used), and the whole application layer protocol is irrelevant to the specific transport network. This standard is irrelevant to communication media.
6 Communication protocol
6.1 Response mode
The complete command is initiated by the requester and answered by the responder, specifically as follows:
1) The requester sends a request command to the responder;
2) After receiving the request, the responder sends a request response to the requester (handshake completed);
3) After receiving the request response, the requester waits for the responder to respond to the execution result; if the requester fails to receive the request response, it will be processed as request response overtime;
4) The responder executes the requested operation;
5) The responder sends the execution result to the requester;
6) The requester receives the execution result and the command is completed; if the requester fails to receive the execution result, it will be processed as execution overtime.
6.2 Overtime retransmission mechanism
6.2.1 Request response overtime
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 System architecture
5 Protocol hierarchy
6 Communication protocol
7 Communication mode between online monitoring equipment and data collection and transmission equipment
Annex A (Normative) Cyclic redundancy check algorithm;
Annex B (Normative) Codes of common monitoring factors and equipment information (extensible)
Annex C (Informative) Examples of communication command and examples of packet disassembly and response mechanism
Annex D (Informative) Calculation method of main pollutants at monitoring points of sewage and flue gas pollution sources
