Modbus RTU

Before using Modbus RTU master or slave, you need to assign a COM port to RTX64, because KINGSTAR Modbus is built on RTX64. The RTU mode supports COM1 and COM2. You can assign either one to RTX64.

Topics:

• Assign a COM port to RTX64
• Return a COM port to Windows

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Assign a COM port to RTX64

1. In Windows, start Device Manager.
2. In Device Manager, expand Ports.



3. Right-click COM1 or COM2 and click Update driver. In this guide we use COM1.



4. Click Browse my computer for drivers.



5. Click Let me pick from a list of available drivers on my computer.



6. In the list of COM ports, click Communications Port (RTX64), and click Next.



NOTE:  If you didn't see the RTX64 port in the list, go back to the Browse for drivers on your computer page. Click Browse. Click C:\Program Files\IntervalZero\RTX64\inf and click OK. Back to the Browse for drivers on your computer page, click Next.





7. The RTX64 driver installs for the COM port. Click Close after the installation is completed.



8. In Device Manager, under RTX64 Drivers, the COM port has been assigned.

Return a COM port to Windows

If you don't need to use a COM port for Modbus RTU communication anymore, do the following to return the COM port to Windows:

1. In Windows, start Device Manager.
2. In Device Manager, expand RTX64 Drivers.



3. Right-click Communications Port (RTX64) and click Update driver.



4. Click Browse my computer for drivers.



5. Click Let me pick from a list of available drivers on my computer.



6. In the list of COM ports, choose the port that doesn't include RTX64 in its name (There are two ports in this guide. Either one is fine.), and click Next.



7. The Windows driver installs for the COM port. Click Close after the installation is completed.



8. In Device Manager, under Ports, the COM port has been returned.