Do the uncontrolled data in the gas transmission pipeline need to be uploaded to SCADA via the station control PLC?
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I am working on expanding a gas pipeline, which is already connected to a SCADA system. The specific work involves adding a distribution station to this pipeline, and a new station control system must be installed; the hardware includes the station control PLC, ESD PLC, workstations, etc. The station is equipped with ultrasonic flow meters (with built-in flow computers), as well as areas related to power distribution for daily operations and production that do not require remote control but need to be monitored. As required by the client, all data from the ultrasonic flow meters and data related to power distribution must be uploaded to the SCADA system. I would like to ask whether the transmission of these data signals must go through the station’s PLC first, or whether they can be transmitted directly to the SCADA control center via communication interfaces without passing through the PLC.
It can all be achieved, right? 1. Upload to SCADA through the PLC itself. It’s just another communication system, but it consumes CPU resources, which affects speed and performance. 2. Don’t you have an operation station? Use it to create an OPC server and then send it over. It is that interface which requires the corresponding OPC settings.
It is likely some pipeline project of CNPC; in fact, this can be done as follows: 1. Upload the data to the SCADA control center via PLC: Third-party data (usually transmitted using MODBUS) is sent to the PLC’s serial port card, and from there the data is uploaded to the control center through the PLC’s communication card. If the PLC used is an AB PLC, the Prosoft MNET communication card can be selected; MNET serves as the data interface between the central system and the station control SCS, with the MODBUS TCP communication protocol being used. If a third party collects too much data, the corresponding performance of the PLC will decline, which needs to be taken into account. 2. Uploaded to the SCADA control center via the station control SCS: This method is quite flexible, and there are many ways to achieve it – DSA (if the center uses an HWL server), OPC (not recommended), IEC (a commonly used protocol), MODBUS TCP, DNP3, etc. Generally, the approach is determined according to the requirements of the control center. Third-party data enters the station control system SCS via a Terminal Server (such as MOXA); the SCS performs protocol conversion (to match the data acquisition protocol of the central SCADA system), and then uploads the data to the control center. That is what used to be commonly referred to as a communication front-end unit, and CEGELEC’s systems still use it in this way today. 3. Transmission to the SCADA control center via a third-party controller or industrial computer: If permitted by the user, a third-party controller (other than a station-level PLC) or industrial computer can be used, as long as it is compatible with the center’s data acquisition protocol. Commonly used ones include BB, ABB, and FOXBORO’s RTU products, but they are rarely used these days as they are somewhat outdated.
It can be easily achieved using a third-party server (MOXA).