VP-EC-RDU

LCD Display Modbus RTU RS485

Field Wiring
Specifications
Menu and Programming Functions
Modbus Functions and Register List

The VP-EC-RDU LCD Display is the perfect addition to any embedded controls system that uses the MODBUS protocol and has an RS485 port. The easy to read 4 line x 20 character display is simple to use. Just write ASCII characters to the applicable holding registers, along with the status LEDs and Audible, and the VP-EC-RDU does the rest.

Each Status LED can be programmed Green, Amber, Red or Off with Solid, Slow Flash or Fast Flash operation. This is perfect for alarm indication in PLC applications. The four user buttons can be read and programmed for different functions as required by the user's application. The local Temperature Sensor located on the main PCB can be read by Modbus Function 03, or can be simply displayed on the LCD.

Standard Features:

Modbus RTU RS845
4 Line x 20 Character LCD
2 Status LEDs
Audible
Menu c/w 4 Pushbuttons
Enclosed and OEM Versions
24 VDC Power
Internal Thermistor Temperature Sensor

Specifications

Item	Metric	Value
I/O	Part Name :	LCD Display Modbus RTU RS485
	Part Number :	VP-EC-RDU
	Temperature Sensor :	Located on the main printed circuit board NTC 10K Ω Thermistor, 3380 Beta Range: -20 to +70 °C (Steinhart-Hart Equation)
	Resolution :	4096 AD Counts (12 bit)
	Accuracy :	+/- 0.5 °C
LCD Display	Format :	20 Character x 4 Lines Type: STN-LCD Blue
	Colour :	White Characters on Blue Background
	Backlight :	LED
Communication	Protocol :	Modbus RTU RS485
	Baud Rate	Programmable 9600 to 115.2K (N81)
	Modbus ID	Programmable ID 1 to 253
	Termination	Jumper Selectable Enable or Disable 120 Ohm
	Wiring	2 RJ45 Jacks, 1 set of terminal blocks (+V, Data A, Data B, Common)
Processor	Processor :	PIC18F Series
Physical	Length :	6.0"
	Width :	4.0"
	Height (Above backplane) :	1.13"
	Weight :	200 g
	Weight, Shipping (Qty. 1) :	300 g
	Enclosure Material :	Flame Retardant ABS, Flame Rating: ULV94V-0
	EnclosureColour :	Black
Electrical	Power Input Voltage Range (Typical :	24 VDC
	Power Input (Minimum) :	9 VDC
	Power Input (Maximum) :	28 VDC
	Power Input Jack :	2.1 x 5 mm Barrel Plug
	Current max :	100 mA
	Current typical :	75 mA
	Isolation :	None
Ambient	Operating Temperature :	-20 to +65 °C
	Storage Temperature :	-40 to +85 °C
	Operating Relative Humidity (non-condensing) :	0 to +95 %RH
	Storage Relative Humidity (non-condensing) :	0 to +95 %RH
	Protection :	IP20
Warranty	Limited Liability :	1 Year From Time of Purchase
	Download :	Warranty Statement

Menu and Programming Functions

To access the MENU and programming functions, press the UP, DOWN and ENTER pushbuttons simultaneously. The basic operation is UP or DOWN to select the display, ENTER to start or exit a function. If the backlight is OFF, any button press will turn the backlight ON.
The user interface is password protected (4 digit PIN). Once entered, the user can select by using the Up, Down and Enter pushbuttons:

Standard Menu Displays:

Display Modbus ID
Display RS485 Baud Rate
Display Local Temperature
Display Software Version
Enter "Setup Program" - Password Required

NOTE: If the user does not press a pushbutton within the "Reset Menu Time", typically 60 seconds, the VP-EC-RDU will return to normal operation and wait for the next valid Modbus command. If no valid commands are transmitted, the VP-EC-RDU will continue to show the last screen displayed. To re-enter the local and programming menus, the user must press UP, DOWN and ENTER simultaneously again.

Temperature Sensor :

There is no calibration required for the Temperature Sensor. The VP-EC-RDU has been programmed with a Steinhart-Hart equation for calculating the temperature value based on the Thermistor reading and Thermistor Beta value (B 0/50 = 3380). A 1% Thermistor is used and typically the accuracy is +/- 1 °C over the operating range of -20 to +70 °C.
The temperature value can be read via Holding Register Address 50 (0x0032).
The reading has a x100 scaler, ie: 25.0 °C would would have a reading of 2500.

Audible :

The VP-EC-RDU has an audible buzzer. The audible can be enabled or disabled from the main menu. When enabled, it provides a "Click" whenever a key is pressed. When turned on by writing a "1" to the Audible Holding Register, the audible will chirp once per second. When enabled and turned ON, it can be silenced by pressing the ENTER pushbutton.

Program Menu Displays:

Program Modbus ID 1 thru 253
Program RS485 Baud Rates (9.6K, 19.2K, 38.4K, 57.6K, and 115.2K)
Adjust and save LCD Contrast
Program LCD Backlight Enable
Status LED Test
Audible Enable
Program Menu Reset Time
Program New Password (Default Password = 0000)

Programming a New Value: After a programming value has been seleected (Passwordm, Modbus ID, etc.), the Cursor ^ will start at the left most digit, and the UP / DOWN buttons are pressed until the desired value is reached. To accept the value, the used presses ENTER and the Cursor will advance to the next digit where the selection process is repeated until all required digits are entered.
For a value of "0000" (the default password value), the ENTER button is pressed 4 times.

Programming Status LEDs:

The VP-EC-RDU has 2 Bi-Colour Status LEDs and 1 BLue Power ON LED.
The Status LEDS have 3 modes of operation and 3 colours:

Code (Hex)	Status LED Operation
0x00	OFF
0x01	GREEN SOLID
0x11	GREEN SLOW FLASH
0x21	GREEN FAST FLASH
0x02	AMBER SOLID
0x12	AMBER SLOW FLASH
0x22	AMBER FAST FLASH
0x04	RED SOLID
0x14	RED SLOW FLASH
0x24	RED FAST FLASH

Reading Pushbuttons:

The VP-EC-RDU has 4 user pushbuttons that can be read via The Status LEDS have 3 modes of operation and 3 colours:

Code (Hex)	Pushbutton Operation
0x00	No buttons pressed
0x08	MENU button pressed
0x04	UP button pressed
0x02	DOWN button pressed
0x01	ENTER button pressed

Modbus Functions and Register List

Function	Description
Function 03	Read Holding Registers
Function 16	Write Multiple Holding Register

Address (Dec)	Address (Hex)	Description	Function
00	0x0000	LCD Line 1 ASCII Character 1 High Byte, Character 2 Low Byte	Read/Write
01	0x0001	LCD Line 1 ASCII Character 3 High Byte, Character 4 Low Byte	Read/Write
02	0x0002	LCD Line 1 ASCII Character 5 High Byte, Character 6 Low Byte	Read/Write
03	0x0003	LCD Line 1 ASCII Character 7 High Byte, Character 8 Low Byte	Read/Write
04	0x0004	LCD Line 1 ASCII Character 9 High Byte, Character 10 Low Byte	Read/Write
05	0x0005	LCD Line 1 ASCII Character 11 High Byte, Character 12 Low Byte	Read/Write
06	0x0006	LCD Line 1 ASCII Character 13 High Byte, Character 14 Low Byte	Read/Write
07	0x0007	LCD Line 1 ASCII Character 15 High Byte, Character 16 Low Byte	Read/Write
08	0x0008	LCD Line 1 ASCII Character 17 High Byte, Character 18 Low Byte	Read/Write
09	0x0009	LCD Line 1 ASCII Character 19 High Byte, Character 20 Low Byte	Read/Write

10	0x000A	LCD Line 2 ASCII Character 1 High Byte, Character 2 Low Byte	Read/Write
11	0x000B	LCD Line 2 ASCII Character 3 High Byte, Character 4 Low Byte	Read/Write
12	0x000C	LCD Line 2 ASCII Character 5 High Byte, Character 6 Low Byte	Read/Write
13	0x000D	LCD Line 2 ASCII Character 7 High Byte, Character 8 Low Byte	Read/Write
14	0x000E	LCD Line 2 ASCII Character 9 High Byte, Character 10 Low Byte	Read/Write
15	0x000F	LCD Line 2 ASCII Character 11 High Byte, Character 12 Low Byte	Read/Write
16	0x0010	LCD Line 2 ASCII Character 13 High Byte, Character 14 Low Byte	Read/Write
17	0x0011	LCD Line 2 ASCII Character 15 High Byte, Character 16 Low Byte	Read/Write
18	0x0012	LCD Line 2 ASCII Character 17 High Byte, Character 18 Low Byte	Read/Write
19	0x0013	LCD Line 2 ASCII Character 19 High Byte, Character 20 Low Byte	Read/Write

20	0x0014	LCD Line 3 ASCII Character 1 High Byte, Character 2 Low Byte	Read/Write
21	0x0015	LCD Line 3 ASCII Character 3 High Byte, Character 4 Low Byte	Read/Write
22	0x0016	LCD Line 3 ASCII Character 5 High Byte, Character 6 Low Byte	Read/Write
23	0x0017	LCD Line 3 ASCII Character 7 High Byte, Character 8 Low Byte	Read/Write
24	0x0018	LCD Line 3 ASCII Character 9 High Byte, Character 10 Low Byte	Read/Write
25	0x0019	LCD Line 3 ASCII Character 11 High Byte, Character 12 Low Byte	Read/Write
26	0x001A	LCD Line 3 ASCII Character 13 High Byte, Character 14 Low Byte	Read/Write
27	0x001B	LCD Line 3 ASCII Character 15 High Byte, Character 16 Low Byte	Read/Write
28	0x001C	LCD Line 3 ASCII Character 17 High Byte, Character 18 Low Byte	Read/Write
29	0x001D	LCD Line 3 ASCII Character 19 High Byte, Character 20 Low Byte	Read/Write

30	0x001E	LCD Line 4 ASCII Character 1 High Byte, Character 2 Low Byte	Read/Write
31	0x001F	LCD Line 4 ASCII Character 3 High Byte, Character 4 Low Byte	Read/Write
32	0x0020	LCD Line 4 ASCII Character 5 High Byte, Character 6 Low Byte	Read/Write
33	0x0021	LCD Line 4 ASCII Character 7 High Byte, Character 8 Low Byte	Read/Write
34	0x0022	LCD Line 4 ASCII Character 9 High Byte, Character 10 Low Byte	Read/Write
35	0x0023	LCD Line 4 ASCII Character 11 High Byte, Character 12 Low Byte	Read/Write
36	0x0024	LCD Line 4 ASCII Character 13 High Byte, Character 14 Low Byte	Read/Write
37	0x0025	LCD Line 4 ASCII Character 15 High Byte, Character 16 Low Byte	Read/Write
38	0x0026	LCD Line 4 ASCII Character 17 High Byte, Character 18 Low Byte	Read/Write
39	0x0027	LCD Line 4 ASCII Character 19 High Byte, Character 20 Low Byte	Read/Write

40	0x0028	STATUS LED 1	Read/Write
41	0x0029	STATUS LED 2	Read/Write
42	0x002A	Audible	Read/Write
43	0x002B	Not Used	Read
44	0x002C	Not Used	Read
45	0x002D	Not Used	Read
46	0x002E	Not Used	Read
47	0x002F	Not Used	Read
48	0x0030	Not Used	Read
49	0x0031	Not Used	Read

50	0x0032	Temperature Deg.C x 100 Scale ie: 25 Deg C reads 2500	Read/Write
51	0x0033	Modbus ID	Read/Write
52	0x0034	Baud Rate	Read/Write
53	0x0035	LCD Contrast Value	Read/Write
54	0x0036	LCD Backlight Enable	Read/Write
55	0x0037	Audible Enable	Read/Write
56	0x0038	Menu Reset Time	Read/Write
57	0x0039	Password	Read/Write
58	0x003A	Pushbutton Values	Read
59	0x003B	Not Used	Read

VP Process Inc.