Modbus Communication: Modbus RTU Practical Application Instructions

Date：2024/03/29

Technical Service Center /Gabriel Li
gabriel@meanwell.com

Modbus is a serial communication protocol released by Modicon Corporation (now Schneider Electric) in 1979 for use with its Programmable Logic Controllers (PLCs). Open to the public, free of copyright restrictions, and simple to implement and manage, Modbus has emerged as a prominent industrial communication protocol standard and is widely utilized for communication between industrial electronic devices. Modbus is merely a protocol framework; there are other versions as well, such as Modbus RTU and Modbus/TCP.

Modbus RTU adopts EIA-485 (or RS-485) differential signals, offering strong anti-noise interference capabilities. The table below provides a comparison between MEAN WELL’s existing communication protocols. The primary distinction from CAN bus is that the Modbus RTU protocol employs a master/slave architecture, thus not supporting multi-host communication.

NOTE: The communication distance of MEAN WELL PMBus is verified at 100KHz, CAN bus is verified at 250Kbps, and Modbus RTU is verified at 115200bps.

MEAN WELL has introduced Modbus RTU into its high-power digital power supply and security power supply product lines, as shown in the table below. 
 

SHP-30K is a programmable digital power supply that supports Modbus RTU communication. Taking SHP-30K-55 as an example, its output voltage can be set to 56V through communication. For detailed instructions, please refer to section 6.3 of the user manual.

MEAN WELL’s digital power supply and security power supply product line offer programmable power settings and charging curves, along with at least two or more communication interfaces (PMBus/CAN bus/Modbus). The flexible setting functions can meet various application needs.
 

For product and application requirements, please contact MEAN WELL distributors or MEAN WELL Technical Service Center.
Also, do not forget to stay tuned for online products and solutions courses on MEAN WELL virtual EXPO.