In the world of industrial automation, Supervisory Control and Data Acquisition (SCADA) systems play a pivotal role in monitoring and controlling large-scale industrial processes. However, acquiring vast amounts of Modbus serial data in Ethernet-based SCADA systems can be complex and challenging. Traditional methods often fall short in meeting the demands of large-scale networks, where speed and efficiency are critical. This article explores the innovative solutions that can dramatically speed up SCADA data acquisition, focusing on the transformative impact of active polling.
The Engineering Challenge
In critical applications like power monitoring systems, SCADA systems depend on receiving timely and accurate data from a multitude of field devices. With traditional polling mechanisms, it could take as long as 30 seconds to complete a polling cycle. Such delays are unacceptable for real-time monitoring and trend analysis, particularly when a polling cycle of three to five seconds is required.
To mitigate this issue, multiple Modbus gateways need to be deployed to shorten polling times. However, this solution can be prohibitively expensive. Consequently, a choice has to be made to substantially increase the budget to meet the acceptable performance levels or endure the slower data acquisition speeds inherent in traditional polling methods.
Solving the Problem with MB3660
The limitations of a round-robin polling method can be mitigated using active polling mechanism. It allows each side of the gateway to operate independently, significantly speeding up the data acquisition process.
Here are the key features
♢ Independent Communication: Each serial port of the gateway acts as a Modbus RTU master, actively polling the Modbus RTU slaves . Simultaneously, the gateway functions as a Modbus TCP server, polled by the SCADA system.
♢ Internal Memory: Gateways with active polling have internal memory that stores data from Modbus RTU devices, facilitating quick data retrieval by the SCADA system.
♢ Faster Polling Cycles: Active polling can make the polling cycle 10 times faster than traditional methods. The SCADA system only needs to handle the Modbus TCP requests and responses, bypassing delays from the Modbus RTU side.
Thus active polling offers several significant advantages
♢ Reduced scan time
♢ Efficient data transfer
♢ Flexibility
Moxa’s MGate MB3660 Modbus gateways exemplify the benefits of active polling. These high port density protocol gateways feature both agent mode and intelligent mode, making data acquisition up to 10 times faster than traditional mechanisms. Whether designing a new system or expanding an existing one, Moxa‘s innovative polling mechanisms ensure efficient and reliable SCADA performance.
For more information on Moxa products and how they can benefit your industry, contact us at lubi@lubielectronics.com.. Our team of experts is ready to help you EMS solution tailored to your specific needs.