Frequently asked questions

FA328755

09 August 2023

Issue: Need to configure Modbus communications between SCADAPack RTU and a Modbus slave device. Then need to poll a Modbus slave device with the SCADAPack RTU
Product Lines:
Series E Configurator
SCADAPack RTU
Environment:
Microsoft Windows XP, Windows Server 2003, Windows Vista, Windows Server 2008, Windows 7, Windows 8, or Windows 10, on 32-bit or 64-bit Operating System
Cause: N/A
Solution:

1. Open Series E Configurator and create a new 535E project.
2. Open the ‘Master’ folder and select the Modbus Scanner page than click on the ‘add device’ button.
3. Give your Modbus slave a name, select the device type you want to use, type in the Modbus unit identifier and the IP address of your device, the listen port is 502.
4. If you did want to communicate via serial you would select Modbus serial RTU then type in the Modbus device address same as for TCP and select the serial port on the RTU that you want to communicate with. Before doing this though you need to configure the port as the Modbus master port. To do this go to the ‘ports’ page and change the desired port to Modbus master, then change the communication parameters to whatever you need them to be for communication
5. Add the points you want to read and write from. To do this click on the ‘add points’ button under ‘Modbus points scanner’. I’m going to select the operation as a read/write parameter as the holding registers I’m targeting are read-writable. I’m going to change Modbus data type from UINT to INT and make the Modbus register start address 48502 I’m targeting the command and frequency reference register of a VSD and their registers are 8501 and 8502 but there is an offset of one so the starting address is 48502. I’m going to leave it as an analog output and change the dnp out point to 8501 because it is easy to remember as this is the holding register of the command. I’ll change the point quantity to 2 as I’m targeting two points.
6. Open the analog points page and see that some of the points have been created automatically.
7. Write configuration to the RTU
8. Read of the RTU and see that the dnp points have been automatically created at 8501 and 8501 as specified.
9. If using TCP, Open the TCP page and give the Ethernet 1 port an IP address that puts your RTU on the same subnet as your Modbus slave device. Also, enable your ‘Modbus client’ checkbox.
10. Write your communication parameters to your RTU.
11. Open point browser and create the DNP points that you are targeting. Mine are 8501 and 8502. Perform a read of the holding registers. yours might still be zero so you won’t see a change. Change the values of the holding registers and perform a write to the slave device. Do a read to see if the value values you attempted to write stayed in the holding registers.