How to Log Weight Scale or Balance to MySQL Database

A complete guide to polling weight scale serial devices and exporting the extracted data directly into a MySQL database.

1. Protocol Configuration: RS232 Weight Scale

Communication Type: Passive Listening (Continuous or Print-on-Demand)

Most industrial scales send ASCII strings terminated by a Carriage Return (CR) and Line Feed (LF). Use the software's 'ASCII Data Parser' module and set the data packet signature to ending characters '#0D#0A'. You can then extract the numeric weight by specifying fixed column positions or using a regular expression. Furthermore, the logger contains pre-defined parsers for the most popular scales.

Apply this base configuration for the serial connection:

{
  "port": "COM1",
  "baud_rate": 9600,
  "data_bits": 8,
  "stop_bits": 1,
  "parity": "none",
  "flow_control": "hardware",
  "packet_end": "#0D#0A"
}

2. Database Setup: MySQL

You will need the MySQL Connector/ODBC installed on the machine running the Data Logger. Create a System DSN pointing to your MySQL server instance.

Use the following SQL script to create your target table. We recommend using the InnoDB engine to handle high-frequency concurrent inserts without table locking.

CREATE TABLE sensor_data (
  id INT AUTO_INCREMENT PRIMARY KEY,
  log_timestamp DATETIME DEFAULT CURRENT_TIMESTAMP,
  device_id VARCHAR(50),
  register_value FLOAT
) ENGINE=InnoDB;

3. Protocol-Specific Troubleshooting

• Garbage characters appearing on the screen: This almost always indicates a baud rate or parity mismatch. 9600-8-N-1 is standard, but older Mettler Toledo or Ohaus scales frequently use 2400 baud or 7-Even-1 parity. Check the hardware manual.
• Is it possible to process stable weight only and ignore intermediate values?: Use one of our filter plugins, and for example, ignore all records without the "stable" signature in a data packet.
• Is it possible to process weight values greater that 100.0 kg?: The Expressions filter plugin allows you to using any math expression For example, the following command: DISCARD_DATA_PACKET_IF(WEIGHT < 100).

4. Database-Specific Troubleshooting

• MySQL server has gone away: If your serial device is idle overnight, MySQL will drop the connection. Enable the 'Keep connection alive' setting in the Data Logger's ODBC export module.
• How can I insert or update a data row for my device?: You can use any SQL query in our 'SQL Database Pro' plugin. In MySQL, you can easily execute the following SQL: 'INSERT INTO ....... ON DUBLICATE KEY .... UPDATE ....'.
• I want to write data from each of my devices to a different table. How can I do it?: In the 'SQL Database Pro' plugin, you can use a placeholder in your SQL. For example, 'INSERT INTO SerialData%DEVICE_ID% (....)'. Before executing SQL, the logger replaces %DEVICE_ID% with the corresponding value from parsed data, and the real destination table will vary (SerialData1, SerialData2, etc.).