Read VFD Speed in PLC through MODBUS

[Shubho]

I have a Delta DVP-14SS PLC. The RS232 serial and RS485 Ports are available in the DVP SS PLC. The PLC is connected with an HMI at RS232 port and a VFD at RS485 (Modbus) port. I want to read the VFD speed in PLC through MODBUS and want to show it in HMI. The register addr of VFD for output frequency is 2103 in Hex. How can I do it?? Plz Help me.

Many thanks..

 

[Tom Jenkins]

It is a two step process. First, the PLC must use a message command to read the speed (and amps and lots of other neat data) from the VFD register and save it in a register in the PLC. Then the HMI must have a tag adressing that PLC register and a display field tied to the tag. The HMI will automatically read the register and show the value.

Note that you will have to do some scaling someplace, as the VFD data may not be in engineering units. That is probably simpler to accomplish in the HMI than the PLC, but that is your choice.