Delta RTU-485 Modbus Remote I/O Communication Module

Warning

⚠️ Please read this instruction carefully before use and follow this instruction to operate the device in order to prevent damages on the device or injuries to staff.

Switch off the power before wiring.

RTU-485 is an OPEN TYPE device and therefore should be installed in an enclosure free of airborne dust, humidity, electric shock and vibration. The enclosure should prevent non-maintenance staff from operating the device (e.g. key or specific tools are required for operating the enclosure) in case danger and damage on the device may occur.

RTU-485 is to be used for controlling the operating machine and equipment. In order not to damage it, only qualified professional staff familiar with the structure and operation of RTU-485 can install, operate, wire and maintain it.

DO NOT connect input AC power supply to any of the I/O terminals; otherwise serious damage may occur. Check all the wirings again before switching on the power and DO NOT touch any terminal when the power is switched on. Make sure the ground terminal [ground symbol] is correctly grounded in order to prevent electromagnetic interference.

Introduction

1. To ensure correct installation and operation of RTU-485, please read this chapter carefully before using your RTU-485.
2. RTU-485 is a Modbus remote I/O communication module for Delta's PLC to remote-control DVP Slim series I/O modules.
3. RTU-485 is a standard Modbus slave device and is compatible with other master devices which comply with Modbus protocol.

Features

• Auto-detecting I/O modules
• Maximum extension: 8 special I/O modules; 128 input points and 128 output points for digital I/O modules

Specifications

DeviceNet Connection

Communication

Mode

Baud rates

1,200bps; 2,400bps; 4,800bps; 9,600bps; 19,200bps; 38,400bps; 57,600bps; 115,200bps

Electrical Specification

Power supply

24 VDC (-15% ~ 20%) (with DC input polarity reverse protection)

Environment

Noise immunity

ESD (IEC 61131-2, IEC 61000-4-2): 8KV Air Discharge, 4KV Contact Discharge

EFT (IEC 61131-2, IEC 61000-4-4): Power Line: 2KV, Digital I/O: 1KV, Analog & Communication I/O: 1KV

Damped-Oscillatory Wave: Power Line: 1KV, Digital I/O: 1KV

RS (IEC 61131-2, IEC 61000-4-3): 80MHz~1000MHz, 1.4GHz~2.0GHz, 10V/m

Operation

0°C ~ 55°C (temperature); 50 ~ 95% (humidity); pollution degree 2

Storage

-25°C ~ 70°C (temperature); 5 ~ 95% (humidity)

Vibration/shock resistance

Standard: IEC 61131-2, IEC 68-2-6 (TEST Fc)/IEC 61131-2 & IEC 68-2-27 (TEST Ea)

Certificates

IEC 61131-2, UL508

Product Profile & Outline

Dimension

Diagram showing the physical dimensions of the RTU-485 module, including length, width, and height, along with mounting hole specifications.

Product Profiles

Diagram illustrating the RTU-485 module's front panel layout and rear connection ports. Key components are numbered:

• 1. POWER indicator
• 2. RUN indicator
• 3. ALARM indicator
• 4. RUN/STOP switch
• 5. Communication indicator
• 6. Address switch
• 7. Communication mode switch
• 8. RS-485 communication port
• 9. Mounting hole for I/O module
• 10. Nameplate
• 11. I/O module connection port
• 12. DIN rail (35mm)
• 13. Fastening hole for I/O module
• 14. DIN rail clip
• 15. Mounting rail for I/O module
• 16. Power input

RUN/STOP Switch

Diagram showing the physical RUN/STOP switch on the module.

Address Switch

The switch is used for setting up the communication address of RTU-485. Range: H'01 ~ H'F0 (decimal: 1 ~ 240).

Example: To set the address to 26, switch DIP switches corresponding to ID4, ID3, and ID1 to "ON".

Note: Set up the address when the power of RTU-485 is switched off. Re-power RTU-485 after setup. Changing the address while operating is invalid. Use a slotted screwdriver carefully.

Diagram showing the DIP switch layout for address setting (ID0 to ID7).

Communication Mode Switch

These switches are for setting up communication format (PA0 ~ PA3, A/R) and baud rate (DR0 ~ DR2).

Communication Format (PA0-PA3, A/R)

Baud Rate (DR0-DR2)

Note: Set up switches when power is off. Changes while operating are invalid. Use a slotted screwdriver carefully.

Basic Operation

Connecting RTU-485 to DVP Slim DI/DO Extension Unit

• Open the fixing clips on top and bottom of RTU-485.
• Align the extension port of Slim DI/DO with RTU-485.
• Press the fixing clips on top and bottom of Slim DIDO to ensure a secure connection.

Diagram showing the physical connection between RTU-485 and DVP Slim DI/DO modules, illustrating port alignment and clip engagement.

Installing RTU-485 and DVP Slim DI/DO on DIN Rail

• Use a 35mm DIN rail.
• Open the DIN rail clip on RTU-485 and Slim DI/DO.
• Insert RTU-485 and Slim DI/DO onto the DIN rail.
• Clip up the DIN rail clips on RTU-485 and Slim DI/DO to fix them securely on the DIN rail.

Diagram illustrating the process of mounting the RTU-485 and Slim DI/DO modules onto a 35mm DIN rail using their respective clips.

Areas for Special Functions

Areas in Digital I/O Module

Areas in Special I/O Module

Note: Maximum 8 special I/O modules can be connected to RTU-485. The first special module connected is the nearest one on the right-hand side of RTU-485.

Special Functions

Error Codes

Function Codes RTU-485 Supports

RTU-485 complies with the standard Modbus protocol, supporting 7 function codes: H'01, H'02, H'03, H'05, H'06, H'0F, and H'10. Refer to the standard Modbus protocol for specific data formats.

Application of RTU-485

Connection between RTU-485 and Master Device

As a standard Modbus slave, RTU-485 is compatible with other programmable logic controllers that comply with Modbus protocol. The example uses DVP-SV PLC as the master. A PC downloads the ladder diagram to DVP-SV via RS-232 (COM1). When DVP-SV executes the program, it sends Modbus commands via RS-485 (COM2) to control RTU-485 remotely. See the figure for connection details.

Diagram showing a typical system connection: a DVP-SV PLC connected via RS-485 to an RTU-485 module, which in turn is connected to various DVP Slim I/O modules (DI/DO, DA, TC, PT) and a special module.

Application Example 1

Scenario: The station No. of RTU-485 is "1". Write "H'0001" into CR#6 of the 1st special I/O module.

This section describes a ladder logic program for the master PLC:

• Initializes communication protocol (9600, 7, E, 1, ASCII) using MOV H86 D1120 and RST M1143.
• Retains communication protocol using SET M1120.
• Sets communication time-out to 300ms using MOV K300 D1129.
• Sets up a sending request using SET M1122.
• Executes a write operation (MODWR K1 H1606 H0001) to write H'0001 into CR#6 of the 1st special module.
• Processes received data (RST M1123).
• Handles communication time-out (RST M1129).
• Ends the program (END).

Diagram illustrating the ladder logic steps for Example 1.

Application Example 2

Scenario: The station No. of RTU-485 is "1". Set up Y0 of the Slim DI/DO on the right-hand side of RTU-485.

This section describes a ladder logic program for the master PLC:

• Initializes communication protocol (9600, 7, E, 1, ASCII) using MOV H86 D1120 and RST M1143.
• Retains communication protocol using SET M1120.
• Sets communication time-out to 300ms using MOV K300 D1129.
• Loads data into registers D100-D108 (e.g., MOV H303A D100). The PLC sends a command like ":01050500FF00F6 CR LF" to RTU-485.
• Sets up a sending request using SET M1122.
• When M0 is ON, the master PLC sends 17 words of data from D100-D108 to RTU-485. The response from RTU-485 is stored in D120-D128.
• Processes received data (RST M1123).
• Handles communication time-out (RST M1129).
• Ends the program (END).

Diagram illustrating the ladder logic steps for Example 2, including the data sent to RTU-485.

LED Indicator & Trouble-shooting

RTU-485 has four LED indicators: POWER, RUN, ALARM, and RS-485, which display the module's status and communication connection.

POWER LED

RUN LED

ALARM LED

RS-485 LED