Learn Learn how to connect to a GS4 Variable Frequency Drive via Modbus TCP in this live Quick Start tutorial Video/Demo from AutomationDirect.com.
This video assumes you have the optional Modbus TCP card installed with current firmware. Check out this video if you need help with that. Parameter 9.44 tells you if a Modbus TCP card is installed. With that com card installed, you can now control the drive via Modbus TCP, RS485 with either Modbus RTU or BACnet (that’s controlled by Parameter 9.86), The terminal strip on the drive, or the keypad. You select how you want to control the drive remotely using parameters 3.0 and 4.0. For our Modbus TCP demo, we want parameter 3.0 to control the run stop and direction via the Modbus TCP com card – and I’m going to choose the option that leaves keypad stop active so I can stop the drive locally even if it is being controlled remotely - and we want parameter 4.0 to control the frequency via the com card. Great, so now when the REMOTE button is pressed and we see the REMOTE icon in the display, the drive is ready to accept commands from the Modbus TCP com card. All we have to do now is configure it to work with our network. I have a little test network setup here in my office that uses this IP configuration. These are the parameters we need to configure the GS4 Drives IP Addressing. So, I’ll set the IP Address to this, Mask to this and Gateway to this so it will be compatible with my network. Remember, your network will probably be different, so don’t assume these values will work for you. If you are uncomfortable with network configuration, then ask your network person for help – they’ll know what numbers to put in here. The GS4 Drive can automatically assign its own IP address using DHCP, but then you have no control over what that will be or how to figure out what it is, so we strongly recommend leaving it set to a STATIC or Fixed IP Address. This is important: We just set all of these communications parameters in the DRIVE. Those need to be copied out to the Modbus TCP com card. You do that by going to parameter 9.64 and entering a 2. I’m going to use a generic Modbus Polling routine I got off the internet called “Modbus Poll” to test the Modbus TCP Communications to the GS4 Drive. Let’s bring that up and establish a connection to the Modbus TCP card. We want to communicate via Modbus TCP and we want to talk to the drive at this IP Address we just setup a minute ago. The defaults are fine for these other items so hit ok. If I look in the GS4 manual, I see that the basic drive parameters start at decimal address 1. That tells us the GS4 Drive uses the Modbus plus 1 addressing convention. So, when we create a new window, we need to be sure to check this box so Modbus poll uses the same addressing. Let’s see what’s at Address one, and let’s display the first 20 items. I’m going to label these so it is easier to see what they are. Well look! We see the Max output voltage is 230, the max rated amps the Base frequency, etc. If I change the rate amps on the key pad, sure enough Modbus Poll sees the change. I could also change the parameter from ModBus poll and see the result on the display. Great, we can read and write parameters. To Control the drive, use this table in Appendix B of the manual. Looks like the Modbus TCP commands start at address 8193. So, lets change the address range to start at address 8193. And I’ll go ahead and label a few of these so we know what they are. Let’s change the drives frequency, we see that appear on the screen. That table in Appendix B says if I put an 18 decimal at address 8193 the motor should run forward. Sure enough, the motor ramps up to speed in the forward direction. Looks like we can reverse direction with a 34 decimal – we see the forward reverse light changed color and the motor reverses direction, and it looks like STOP is a 1, so if we enter that ... the motor ramps down and stops. Perfect. Well, that’s all there is to it. Install the optional Com card. Set the drive IP Configuration to something that is compatible with your network Choose static IP whenever possible And copy those parameters from the drive parameters to the Modbus TCP com card. And finally, to control the drive remember to set parameters 3.0 and 4.0 to point to the com card. Then you just use that Modbus TCP Table in Appendix B to issue the commands. Click here to learn more about theGS4 drive. Click here to learn about AutomationDirect’s free support options. Click here to subscribe to AutomationDirect’s YouTube channel so you will be notified when we publish new videos.