Using Modbus RTU on PowerFlex 520 series drives

Summary

Using Modbus RTU on PowerFlex 520-Series drives

Environment

• PowerFlex 523
• PowerFlex 525

Answer

Yes, you can use the RS485 (DSI) protocol. The following PowerFlex 520-Series drive parameters are used to configure the drive to operate on a DSI network.

Parameter Details Reference

•       Parameter P046 [Start Source 1]: Set to 3 “Serial/DSI” if Start is controlled from the network.
•       Parameter P047 [Speed Reference 1]: Set to 3 “Serial/DSI” if the Speed Reference is controlled from the network.
•       Parameter C123 [RS485 Data Rate]: Sets the data rate for the RS-485 (DSI) port. All nodes on the network must be set to the same data rate.
•       Parameter C124 [RS485 Node Addr]: Sets the node address for the drive on the network. Each device on the network requires a unique node address.
•       Parameter C125 [Comm Loss Action]: Selects the drive’s response to communication problems.
•       Parameter C126 [Comm Loss Time]: Sets the time that the drive will remain in communication loss before the drive implements C125 [Comm Loss Action].
•       Parameter C127 [Comm Format]: Sets the transmission mode, data bits, parity, and stop bits for the RS485 (DSI) port. All nodes on the network must be set to the same setting.
•       Parameter C121 [Comm Write Mode]: Set to 0 “Save” when programming the drive. Set to 1 “RAM only” to write only to volatile memory.

For more information, refer to the PowerFlex 520-Series Adjustable Frequency AC Drive User Manual, Publication 520-UM001, Appendix C.