Starting at $416.00
  • Usually ships in 2-3 weeks



  • Compatible with all versions of the 9900
  • Connects to PLCs and SCADA systems
  • Live, primary & secondary readings
  • Provides sensor status
  • Modbus RTU & ASCII modes
    • RTU is default mode
  • 1200 to 115200 baud rates
    • 19200 is default baud rate
  • Parity selections:
    • Even, odd, or none
    • Even is default parity
  • 12 to 24VDC power


The GF Signet 9900 modbus module allows any 9900 transmitter to transfer live readings, units of measure, and measurement status information to external PLC and SCADA systems, or any other device that supports the Modbus Protocol. The modbus module supports the serial modbus RS485 standard, allowing up to 32 devices on a single pair of wires.

Modbus communication to control systems has many advantages over 4 to 20 mA current loops such as multiple readings, multiple devices on a single pair of wires, and measurement error messages to indicate the quality of data. The 9900 modbus module will communicate is there is a missing sensor, missing probe, or wrong sensor, and confirm whether a reading is good.

The modbus module is compatible with the relay module, direct conductivity module, and the current loop module. The batch module can be installed with the modbus module, but no readings will be sent when the 9900 is set to the batch instrument.

Typical applications include wastewater treatment, reverse osmosis, deionization (ultrapure water, two bed and mixed bed system), chemical manufacturing and addition, metal and plastic finishing, fume scrubber, cooling towers, media filtration, and aquatic life support.