Polling And Logging Weight Scale Device to Postgre SQL

A complete guide to read data from RS232 weight measuring serial devices and exporting parsed values directly into a PostgreSQL database with your database structure.

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: PostgreSQL

Install the PostgreSQL ODBC Driver (psqlODBC) on the server running Advanced Serial Data Logger. Create a System DSN or use a direct connection string in the SQL Database Professional plugin like 192.168.1.100:mydatabase.

Use the following SQL script to create your target table. Ensure your user role has INSERT privileges for the target schema. Use the NUMERIC data type to prevent floating-point precision loss from raw sensor data.

CREATE TABLE rs232_logs (
  id SERIAL PRIMARY KEY,
  log_timestamp TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  device_name VARCHAR(50),
  extracted_value NUMERIC(10, 2)
);

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

• FATAL: password authentication failed: Verify that your pg_hba.conf file allows connections from the Data Logger's IP address (if remote) and that the authentication method is set to md5 or scram-sha-256.
• I have two similar records with the same timestamp in my database for every record: Verify that you do not use two data export plugins at the same time. For example, ODBC Database and SQL Database Pro because they can export your data in parallel.
• I've installed ODBC drivers and created a DSN, but your software does not allow me to select it.: Our software requires 32-bit ODBC drivers. Therefore, you should install this version of drivers to create a DSN in the 32-bit ODBC Administrator. You can use the 'Setup' button in the 'ODBC Database' plugin to do it.