Troubleshooting serial com 3-5 – Yaskawa F7 Modbus User Manual
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Troubleshooting Serial COM 3-5
4:
Send a message from the controller to the F7 drive.
4.1:
Connect an oscilloscope between the F7 drive’s R+ and R- terminals for RS422/RS485 4-wire networks or between
terminals R+/S+ and R-/S- for RS485 2-wire networks.
4.1.1:
Verify that the message pulse train exists and contains the correct number of pulses. Refer to the chapter
Message Formats for information on the message contents.
4.1.2:
Verify that the signal levels adhere to the RS422/RS485 standard.
4.2:
Insert a data analyzer in the RS422/RS485 circuit and capture the message sent by the controller in a hexadecimal
format Record the command message below.
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4.3:
Verify that the contents of the message adheres to the MODBUS format as described previously.
4.3.1:
Verify that the node address is valid.
4.3.2:
Verify that the function code is valid
4.3.3:
Verify that the register address is valid
4.3.4:
Verify that the number of data bytes is correct is valid
4.3.5:
Verify that the CRC is correctly calculated.
4.3.6:
Verify that the message requires a response.