When upgrading a tank, keeping the existing Pt100 sensor can be combined with three requirements: temperature in the PLC, local threshold signalling and a history on the PC. The ATSEN design scenario follows this measurement chain from the sensor to data recording in ATSEN Optimetria.
Temperature conversion and threshold signalling
PR 4116 from PR electronics has a separate 24 V direct current (DC) supply. It provides the Pt100 measuring current and converts the sensor resistance into a 4…20 mA signal. The active output connects to a passive PLC input; the total permitted load is no more than 800 Ω.
Two relays provide threshold signalling. Their potential-free contacts switch an externally powered circuit, which must remain within the contact ratings. Follow the converter supply, analogue signal path and relay-switched circuit separately in the wiring diagram.
The communication path to the PC
Data access requires the optional PR 4511 front module, with a detachable display for configuration and diagnostics. Communication to Optimetria uses Modbus RTU over RS-485 and a compatible USB–RS-485 interface. The software displays values, retains their history and exports CSV data for Excel.
Commissioning checks
Configure communication, registers and scaling, then compare the temperature shown in the PLC with the value read on the PC. Check threshold signalling as well. The history should allow the relevant temperature deviation to be found after an alarm. Receiving a signal in the PLC alone does not confirm that the separate communication and recording path has been configured correctly.
Source: ATSEN LinkedIn post, published on 19 October 2026.