GA500 drives have a built-in self-diagnostic function for the serial communication (Modbus) interface. Under certain circumstances, it may be necessary to test this circuitry.

To perform the self-diagnostic test on a GA500 drive, follow the steps below:

1. Apply power to the drive.
2. Set parameter H1-06 = 67 (S6 terminal) for Communications Test Mode.
3. Remove power to the drive.
   • Caution: It is recommended to verify 10VDC or less is present on the DC bus before performing any service work.
4. Wire the drive as shown in the figures below. Jumper S6 to SN terminals. Verify a jumper between SC and SP is present (factory).
   
5. Apply power to the drive and view the keypad (display).
   • If the drive displays a "PASS," the drive serial communications is operating normally.
   • If the drive displays a "CE" (Communication Error), the drive serial communications failed and the drive will need to be repaired or replaced.
6. Remove power to the drive.
   • Caution: It is recommended to verify 10VDC or less is present on the DC bus before performing any service work.
7. Remove the wire jumpers from terminals S6 and SN terminals. Set parameter H1-06 (terminal S6) back to default.
8. Return to normal operation.