PPT-1 Position Transmitter

Overview

Read a potentiometer's position without loading its circuit.

The PPT-1 reads the position of a potentiometer that is already powered by 28 V DC or 28 V AC (400 Hz typical) and shows it on a panel display and over Modbus RTU. It samples the wiper and the excitation at the same instant, so the reading is a true ratio and does not move when the excitation voltage changes.

Each input is over 5 MΩ, so the PPT-1 can sit alongside an existing indicator or controller without loading the sensor. It accepts ±50 V between the pot circuit and its own ground, and 90 V gas discharge tubes to PE protect the input from surges on field wiring.

Choose %, mm or degrees, set zero and full scale with the CAL key, and read position, excitation and fault status from a Delta (or any Modbus RTU master) HMI over isolated RS-485. It fits a standard 144 × 72 mm DIN panel cut-out.

DC or AC excitation

10–51 V

Input impedance

> 5 MΩ

Position updates

10 / s

RS-485 Modbus RTU

Isolated

Why engineers choose the PPT-1

• Ratiometric readingWiper and excitation sampled together by a 24-bit ADC, so supply swings don't shift the position.
• DC or AC excitation10–51 V peak, DC or AC from about 25 Hz to 1 kHz, including 28 V DC and 28 V AC 400 Hz.
• Doesn't load the sensorOver 5 MΩ per input, ±50 V common-mode range and 90 V gas discharge tubes to PE.
• Clear front panel1.3" OLED with position, bar graph, excitation type, frequency, voltage and status.
• Two-step calibrationMove to zero, press; move to full scale, press. Stored in EEPROM, from the panel or over Modbus.
• Fault detectionFlags lost excitation, an open or out-of-range wiper and over-range, with a red FAULT lamp.
• Isolated Modbus RTURS-485 at 9600, 19200 or 38400 baud with function codes 03, 04, 06 and 16.
• Quick wiringPluggable 5.08 mm terminals on the rear for power, sensor and RS-485.