YASKAWA P7, User Manual, Page: 228 / 256

Communications D - 14
Modbus Self-Diagnosis
The Drive has a built-in function for self-diagnosing the operations of serial communication interface circuits. The
self-diagnosis function connects the communication parts of the send and receive terminals, receives the data sent by the
Drive, and checks if communication is being performed normally.
Perform the self-diagnosis function using the following procedure.
1. Turn ON the power supply to the Drive, and set parameter H1-05 (Terminal S7 Function Selection) to 67 (Comm Test
Mode).
2. Turn OFF the power supply to the Drive.
3. Perform wiring according to the following diagram while the power supply is turned OFF.
4. Turn ON the terminating resistance. (Turn ON pin 1 on DIP switch 1.)
5. Turn ON the power supply to the Drive again.
Fig. D.10 Communication Terminal Connection for Self -Diagnosis Function
6. During normal self-diagnostic operation, the Digital Operator displays the frequency reference value. If an error occurs, a
CE (Modbus communication error) alarm will be displayed on the Digital Operator, the fault contact output will be turned
ON, and the Drive operation ready signal will be turned OFF.