Pro-face RHAA009: Cannot use the port

Pro-face HMI Critical Communication

Model: GP4000/SP5000 Series | Code: RHAA009

Applicable Systems
GP4000 Series

Symptoms

  • GP-Pro EX display unit shows error RHAA009: Cannot use the port.

Possible Causes

  • Two or more driver types were selected for an identical COM port, or the USB/SIO (RS-422/485) port flow control setting is incorrect.

Troubleshooting Steps

  1. Step 1: Check the Port settings in GP-Pro EX Device/PLC. When using a USB/RS-422/485 conversion adapter, set Flow Control to None.
    Communication restored and error cleared

How to Reset

Repower or reset the display unit after correcting the root cause.

Related Pro-face Fault Codes

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Source: Pro-face GP-Pro EX Maintenance/Troubleshooting Manual, T.7.1 Common Display errors (proface.tech/otasuke official)

Category: HMI