The Otis GAA21750AK3 is essentially a dedicated service debugger (also often referred to as a service tool) for Otis elevators, which is mainly used for elevator parameter setting, troubleshooting, and other operations. To use it, you first need to familiarize yourself with the key functions, and then complete the connection and subsequent debugging in accordance with the specifications. The specific methods are as follows:

1. Familiarize Yourself with Key Functions
The debugger has a total of 16 keys, divided into left and right parts. The 4 keys on the left are responsible for menu level switching, and the 12 keys on the right are composite function keys that need to work with the blue key to implement different functions. Details are as follows:
| Key Area | Key Name | Function Description |
| Left Key Area | MODULE | Directly return to the main menu of the service tool from any interface |
| FUNCTION | Return to the installation and maintenance function menu to facilitate the selection of different control systems | |
| SET | Return to the item menu in the function interface for further selection of installation or maintenance-related sub-functions | |
| Blue Key | Equivalent to the Shift key. When pressed, a blinking cursor will appear at the position of the first character on the display. At this time, pressing the right keys can trigger the functions of the blue part. The cursor disappears after the key operation | |
| Right Composite Key Area | CLEAR | Press it alone to erase the last incorrectly entered digit; press it together with the blue key to be equivalent to the Enter key, which is used to save the entered or modified value |
| GO ON/GOBACK | Press GO ON alone to switch the display forward step by step; press this key after pressing the blue key to realize the function of GO BACK to switch the display backward | |
| Numeric Keys (4 - 9, etc.) | Press them alone for regular numeric functions; when used with the blue key, Shift + 4 corresponds to hexadecimal number A, Shift + 5 corresponds to B, Shift + 6 can change the value sign or correspond to hexadecimal number C, Shift + 7 corresponds to D, Shift + 8 corresponds to E, and Shift + 9 corresponds to F |
2. Connection and Self-test
Align the debugger interface with the matching interface on the Otis elevator control board and insert it. After insertion, the debugger will automatically perform a self-test. If the display shows "SELF TEST –OK MECS - MODE", it indicates that the self-test has passed and the current connection is in Modular Elevator Control System mode. The connection is normal, and debugging can be started. If other words are displayed, first unplug the debugger and reinsert it to try again. If the problem persists, it may be due to a debugger fault or damage to the elevator control board interface.

3. Core Debugging Operations
Parameter Viewing and Modification: Enter the corresponding menu level by level through the MODULE, FUNCTION, and SET keys to find the parameter setting module. When you need to enter a value, directly press the right numeric keys to input; if you make an input error, press the CLEAR key to delete the incorrect digit. After completing the modification, press the blue key + CLEAR key to save the changes. If you need to enter a hexadecimal number, you can use the blue key with the corresponding numeric keys.Status Viewing and Switching: During debugging, press the GO ON key to gradually view various operating parameters and status data of the elevator forward; if you need to look back at the previous parameters, you can use the blue key + GO ON/GOBACK key to switch the display backward, which is convenient for comparing the elevator operating data at different time periods.

4. Post-debugging Follow-up
After completing the parameter setting or troubleshooting, you can return to the main menu through the MODULE key, and then disconnect the debugger from the elevator control board. If you have modified key parameters, it is recommended to enter the corresponding menu again to check the parameter values to ensure that the saving takes effect, so as to avoid elevator operation failures caused by abnormal parameters.
Please note that elevator debugging is related to safe operation. Before the operation, ensure that the elevator is in inspection mode to prevent accidental operation of the elevator during debugging. Before modifying parameters, it is recommended to record the original parameters so that the initial state can be restored if an error occurs during debugging.

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Contact person: Candice
Email: candice@nonaelevator.com
Contact Phone: (86) 17719527681(Whatsapp/Wechat)
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Company Name: Shaanxi Nona Elevator Parts Co., Ltd.
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Country: China
Website: https://www.nonaelevator.com/