ModbusTCP Status, Monitor, and Troubleshooting

This procedure will walk through verifying, monitoring, and troubleshooting read/write communications between the LS XEM PLC and a drive using the Modbus TCP protocol.

In this example, we will confirm communications between the LS XEM PLC and Ironhorse ACN VFD.

  1. Go Online with the XEM Processor.

  2. Go to Online menu è Communication Module Setting and Diagnosisè System Diagnosis.

System Diagnosis Window

  1. In the System Diagnosis window, right-click on the Ethernet Port, then choose Status by Service.

  2. Choose the P2P Service tab.

  1. Enable Online Monitor.

  2. Select any Monitor window.

  3. Type the direct memory addresses into the Variable/Device field.

  4. Right-click the Value field to change from Hexadecimal to Signed Decimal.

  1. Double-click the Value field.

  2. Enter the frequency value in %MW900, 1010 = 10.1 Hz. Select OK. This value will write to the drive.

  3. Run the drive via drive keypad.

  4. Monitor %MW800/801 to see the actual current and output frequency of the drive match the commanded frequency.

If you are unsure which PLC memory registers are used or want to see a summary. Use the following:

  1. Go to the Used Device window.

  2. Click Refresh.

  3. Choose the memory type. In this case M and click OK. The program will tell you each location the memory address is used. Instances in the Project Configuration will show up as well as the programming tasks.

  4. Double-click each instance to see where in the program it is located. We can see in this example %MW800 is located in the P2P Block area , Index 0.

  5. Click Go to to open the P2P Block config window.

 

 

 

 

 

 

LP202