nmpds (Customer) asked a question.
Help a beginner control GS20 frequency via Ethernet IP?
I have previously programmed GS20 drives with discrete inputs and analog frequency control via PLC. My newest project requires frequency control via Ethernet IP (start/stop signals are still controlled via discrete inputs). I am brand new to Ethernet IP and am struggling to figure it out.
Should frequency be controlled via explicit or implicit messaging?
What are the exact parameters that I need to send to change the frequency?
How is this typically done within a PLC ladder logic program?
For reference, I am using a Keyence KV-8000A PLC.
I've never used that Keyence PLC before but here's a good explanation of the EIP communications differences:
https://library.automationdirect.com/ethernetip-implicit-vs-explicit-messaging/
In a nutshell:
Explicit: Send a small amount of data and wait for a response. Must be sent through a ladder function.
Implicit: Set up to send a block of data and receive a block of data continuously.
I normally use implicit comms since it's more convenient. The data going out and coming back is mapped to PLC memory.
Here's the comms guide for the GS20 drive:
https://cdn.automationdirect.com/static/manuals/gs20m/appxb.pdf
See page B-20 for the important implicit settings you'll use to set up your EIP comms on the PLC end.
O=originator (PLC) or master
T=Target (Drive) or slave
There are assembly instances, 100 and 100 in this case.
100 is your PLC's 'output buffer' and is 3 words of data (data type 16 bits, size of 3). This is being sent to the drive from your PLC.
101 is your PLC's 'input buffer' and is 16 words of data (data type 16 bits, size of 16). This is being received from the drive to your PLC.
102 is a configuration instance and is many times not used (hence the data type of 8 bit, size of 0.)
Page B-22 shows the data for instance 100. Looking at the first word (0), you can see bits 0-5 pertain to jogging or running the drive. word 1 is the freqeuncy to run at.
Page B-23 shows the data for instance 101. This will tell you what's happening with the drive. Word 1, bit 12 will be on if the drive is running. 0 if stopped. Word 3 will show the output frequency (should change when drive is accel or decelerating).
Let me know if this helps.
The easiest implementation for GS20 is to use implicit messaging. The GS20 implicit messages provides pre-defined structures: 3 words for Control and 16 words for status. This is adequate for most applications. See the pre-defined registers on page B-22, B23 of the GS20 manual.
See page B-14 for parameter setup of GS20 for EtherNet/IP.
This example below is for the LS XEM PLC, but this should give you an idea of how to setup implicit communications on GS20.
https://cdn.automationdirect.com/static/helpfiles/ls_plc/Content/C_ProcedureTopics/LP207.htm
Also, for ADC PLCs, we have sample programs already built for EIP communications. They are in the downloads section of the drive item page on the webstore.