VP-EC-RDU-MINILCD Display Modbus RTU RS485

Model VP-EC-RDU-MINI Modbus RTU LCD Display 4 Line x 20 Character, RS485, with Temperature Sensor

Regular price $47.95 USD Sale

The VP-EC-RDU-MINI Remote Display by VP Process Inc. is the perfect addition to any controls system or project that uses the MODBUS RTU protocol and RS485.

The easy to read 4 line x 20 character display is simply written to by writing the applicable holding registers. The three user buttons can be read and can be programmed for different functions as required by the user's application. Arduino and Raspberry Pi projects can also use the VP-EC-RDU-MINI when using the Arduino and Raspberry Pi serial ports as RS485.

As an added Bonus, the VP-EC-MINI has an on board temperature sensor (10K Thermistor) which can also be read by Modbus Functions.

For complete details on all of our Modbus Interfaces, please visit our website at www.vpprocess.com


  • Low Power (9 - 24 VDC typical, max 28 VDC)
  • LCD Display 4 Line x 20 Character, White Characters, Blue Background (Other colors available upon request)
  • Blue Power On Led
  • 3 User Pushbuttons  (Up, Down, Enter)
  • RS485 Interface 2 RJ45 (Cat5e), 2 x 4 Pt. Terminal Block
  • Programmable Baud Rates ( 9.6K,19.2K, 57.6K and 115.2K Baud N81 )
  • 6-32 Mounting Hardware Included
  • Modbus ID Programmable
  • Modbus RTU Protocol
  • 4x20 LCD Backlight Programmable  Always ON, Timed Off
  • Simple Operation Read and Write Modbus Holding Registers
  • Dimensions 3.9" x 2.4" x 1.5"
  • Microchip PIC18F Series Processor c/w ICSP connection
  • Arduino and Raspberry Pi compatible when using RS485 with Arduino and Raspberry Pi projects

MODBUS Functions

Function 03 - Read Holding Registers

Function 16 - Write Holding Registers

Display Connected to Raspberry Pi with RS485 Connection


Controller Module - VP-EC-RDU-MINI Rear View

Programming the VP-EC-RDU-MINI

To enter Program mode, the three pushbuttons are pressed all at once. Once entered, the programmable menu's are password protected. After entering the 4 digit PIN number (defaults to 0000 from the factory) is entered, the following items can be programmed:

  1. Modbus ID (Values 1 thru 253)
  2. Baud Rate (9.6K, 19.2K, 5764K 115.2K)
  3. LCD Contrast
  4. LCD Backlight Enable (Modbus Control)
  5. Menu Reset Time (Seconds before reverting to normal operation if PB's not pressed)
  6. Password (4 digit Pin - 0000 to 9999)


Download the User Manual

VP-EC-RDU-MINI User Manual

 Download Python Sample Code for the Raspberry Pi 3

pispi_rdu_lib.py  VP-EC-RDU-MINI Python Library (Same as VP-EC-RDU)

pispi_rdu_mini_test.py  VP-EC-RDU-MINI Python Sample Test Code