Can we directly monitor Powerflex drive parameter and even Start Stop and Set the speed Reference from HMI without additional PLC hardware?
Yes can. Let say, there is existing standalone Powerflex drive & You want to monitor drive parameter through HMI, complete with Trend and Alarm Log.
Then It can be implemented using these 2 option:
Using Modbus RTU
This communication can be applied on Powerflex Drive that has RS485 port with Modbus RTU communication such as Powerflex 525 Drive.
The good thing about it, not only can monitor and edit drive parameter but also can control drive such as Start Stop or set drive speed reference.
Since Powerflex 525 has built in PID Control & analog input, it means PID control application with HMI without additional PLC Hardware can be done.
Example: To start drive,we can toggle bit 1 of Logic command parameter with address 2000H (8192 Decimal) on Powerflex Drive.
Check “Powerflex 520 Series Adjustable Frequency AC Drive” user manual at Appendix C for information on how to setup Modbus RTU on the drive.
Using Ethernet/IP Explicit Messaging
This Communication can be implemented on any Powerflex Drive that has Ethernet/IP port.
This include Powerflex 525, Powerflex 755, Powerflex with 20-COMM-E ethernet module (eg. Powerflex DC with 20-COMM-E module).
FactoryTalk View (FactoryTalk Linx version >6.2) and non-Rockwell HMI that has Ethernet/IP Explicit Messaging driver can connect to Powerflex Drive.
PC with Python program also can.
To read and write single Powerflex drive parameter, need to set the Ethernet/IP addressing information that include Class, Instance and Attribute data.
Example:To write or read single parameter data value on VFD or drive, we set:
Class = 93(Hex.) = 147(Dec.),
Instance = Drive Parameter number,
Attribute = 9(Hex.) = 9(Dec.).
The information about Class, Instance and Attribute can found on drive manual.
When using FactoryTalk View to connect to Powerflex Drive, Device Shortcut Type at Communication Setup, need to be set as ‘CIP object’ instead of ‘Processor’
CIP object need to set as ‘Class/Instance/Attribute Message’.
Explicit Messaging can be used to start stop Drive too, but additional programming to prevent adapter faulted on time out is needed.
Some HMI can do this.
𝗦𝗼𝗺𝗲 𝗹𝗶𝗺𝗶𝘁𝗮𝘁𝗶𝗼𝗻 𝘄𝗵𝗲𝗻 𝗰𝗼𝗻𝗻𝗲𝗰𝘁 𝗛𝗠𝗜 𝘁𝗼 𝗗𝗿𝗶𝘃𝗲:
When write parameter data to Nonvolatile Storage (NVS) frequently. The NVS can quickly exceed its life cycle and cause the drive to malfunction.
When control drive from HMI, HMI can not detect loss of communications to the drive and trigger the Emergency Stop. Therefore, all equipment used in this manner, should be subject to a risk assessment.
Ethernet/IP Explicit Messaging is nondeterministic and intended for non-time critical communication.
