DELTA RTU-485 Modbus Remote I-O Communication Module Instruction Manual

: June 9, 2024
: Delta

Table of Contents

DELTA RTU-485 Modbus Remote I-O Communication Module
Product Information
Features
Specifications
Product Usage Instructions
Basic Operation
Function Codes RTU-485 Supports
Application of RTU-485
Introduction
Product Profile & Outline
Basic Operation
Areas for Special Functions
Function Codes RTU-485 Supports
Application of RTU-485
- Application Example
LED Indicator & Trouble-shooting
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DELTA RTU-485 Modbus Remote I-O Communication Module

Product Information

Modbus Remote I/O Communication Module RTU-485

The Modbus Remote I/O Communication Module RTU-485 is a product designed to remotely control DVP Slim series I/O modules using Delta’s PLC. It is a standard Modbus slave device and is compatible with other master devices which comply with the Modbus protocol. The device has an auto-detecting I/O module feature, and the maximum extension is 8 special I/O modules, 128 input points, and 128 output points for digital I/O modules. The device has a 24VDC power supply (with DC input polarity reverse protection).

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
Transmission method: RS-485
Electrical isolation: 500 VDC
Interface: Removable connector (3Pin)
Transmission cable: 2-wire twister shielded cable
Communication mode: RTU, ASCII
Baud rates: 1,200bps; 2,400bps; 4,800bps; 9,600bps; 19,200bps; 38,400bps; 57,600bps; 115,200bps
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

Product Usage Instructions

Before using the Modbus Remote I/O Communication Module RTU-485, it is important to read the manual carefully and follow the instructions to prevent damage to the device or injuries to staff.

Basic Operation

Switch off the power before wiring. The RTU-485 is an OPEN TYPE device and therefore should be installed in an enclosure free of airborne dust and humidity. The following steps should be followed for basic operation:

Connect RTU-485 to DVP Slim DI/DO Extension Unit
Install RTU-485 and DVP Slim DI/DO on DIN Rail

Function Codes RTU-485 Supports

The RTU-485 supports the following function codes:

01: Read Coil Status
02: Read Input Status
03: Read Holding Registers
04: Read Input Registers
05: Force Single Coil
06: Preset Single Register
0F: Force Multiple Coils
10: Preset Multiple Registers

Application of RTU-485

The RTU-485 can be used in the following applications:

Connection between RTU-485 and Master Device
Application Example

Introduction

To ensure correct installation and operation of RTU-485, please read this chapter carefully before using your RTU-485
RTU-485 is a Modbus remote I/O communication module for Delta’s PLC to remote-control DVP Slim series I/O modules.
RTU-485 is a standard Modbus slave device and is compatible with pther 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
**** Transmission method| RS-485
---|---
Electrical isolation| 500 VDC
Interface| Removable connector (3Pin)
Transmission cable| 2-wire twister shielded cablew8
Communication

Mode

|

ASCII

| 7, E, 1| 7, O, 2| 8, O, 1
---|---|---|---|---
7, O, 1| 7, N, 2| 8, N, 1
7, E, 2| 8, E, 1| 8, N, 2
RTU| 8, E, 1| 8, O, 1| 8, N, 1| 8, N, 2
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| 0ºC ~ 55ºC (temperature); 50 ~ 95% (humidity); pollution degree 2
Storage| -25ºC ~ 70ºC (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

Product Profiles

POWER indicator
RUN indicator
ALARM indicator
RUN/STOP switch
Communication indicator
Address switch
Communication mode switch
RS-485 communication port
Mounting hole for I/O module
Nameplate
I/O module connection port
DIN rail (35mm)
Fastening hole for I/O module
DIN rail clip
Mounting rail for I/O module
Power input

RUN/STOP Switch

RUN/STOP action	Explanation
RUN	I/O module in RUN mode
RUN → STOP	1. I/O module switches from RUN to STOP.

2. Output points on digital I/O module all turn Off.

STOP

| 1. Special I/O module in STOP mode

2. Special I/O module cannot be controlled by communication.

3. Digital I/O module cannot be controlled by communication.

STOP → RUN

| 1. Special I/O module switches from STOP to RUN.

2. RTU-485 redetects the number of points in Slim DI/DO and the number of special I/O modules.

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

Switch setting	Content

H’01 ~ H’F0

| Valid communication address

ID0 ~ ID7 are defined as: 20, 21, 22, …26, 27

H’00, H’F1 ~ H’FF|

Invalid communication address

Example: If you need to set the address of RTU-485 to 26, swich the DIP switch corresponding to ID4 to “ON”, switch corresponding to ID3 to “ON” and switch corresponding to ID1 to “ON”.
Note:

Please set up the address when the power of RTU-485 is switched off. After the setup is completed, re-power RTU-485.
When RTU-485 is operating, changing the setting of communication address will be invalid.
Use slotted screwdriver to adjust the switch carefully in case you scratch the switch.

Communication Mode Switch
These switches are for:

Setting up communication format (PA0 ~ PA3, A/R)
Setting up baud rate (DR0 ~ DR2)
PA3| PA2| PA1| PA0| A/R| Format
---|---|---|---|---|---
OFF| OFF| OFF| OFF| ON| 7,E,1, ASCII
OFF| OFF| OFF| ON| ON| 7,O,1, ASCII
OFF| OFF| ON| OFF| ON| 7,E,2, ASCII
OFF| OFF| ON| ON| ON| 7,O,2, ASCII
OFF| ON| OFF| OFF| ON| 7,N,2, ASCII
OFF| ON| OFF| ON| ON| 8,E,1, ASCII
OFF| ON| ON| OFF| ON| 8,O,1, ASCII
OFF| ON| ON| ON| ON| 8,N,1, ASCII
ON| OFF| OFF| OFF| ON| 8,N,2, ASCII
OFF| ON| OFF| ON| OFF| 8,E,1, RTU
OFF| ON| ON| OFF| OFF| 8,O,1, RTU
OFF| ON| ON| ON| OFF| 8,N,1, RTU
ON| OFF| OFF| OFF| OFF| 8,N,2, RTU
DR2| DR1| DR0| Baud rate (bps)
OFF| OFF| OFF| 1,200
OFF| OFF| ON| 2,400
OFF| ON| OFF| 4,800
OFF| ON| ON| 9,600
ON| OFF| OFF| 19,200
ON| OFF| ON| 38,400
ON| ON| OFF| 57,600
ON| ON| ON| 115,200

Note:

Please set up the switch when the power is switched off. After the setup is completed, re-power RTU-485.
When RTU-485 is operating, changing the setting of the switch will be invalid.
Use slotted screwdriver to adjust the switch carefully in case you scratch the switch.

Basic Operation

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

Open the fixing clips on top and bottom of RTU-485. Meet the extension port of Slim DI/DO with RTU-485.
Press the fixing clips on top and bottom of Slim DIDO and check if the connection is fine.

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

Use 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 on the DIN rail, as shown below.

Areas for Special Functions

Areas in Digigal I/O Module

Communication address	Devices	Attribute	Data type	Length
H’0400 ~ H’047F	X: X000 ~ X177 (Octal)	R	bit	128 points
H’0500 ~ H’057F	Y: Y000 ~ Y177 (Octal)	R/W	bit	128 points

Areas in Special I/O Module

Communication address	Devices	Attribute	Data type	Length
H’1600 ~ H’1630	1st special I/O module: CR0 ~ CR48

Please refer to theCR attribute of each special I/O module.

Note: Maximum 8 special I/O modules are connectible to RTU-485. The first special module connected is the
nearest one on the right hand side of RTU-485, and so on.

Special Functions

Communication address	Attribute	Content	Explanation
H’0000	R	Model name	Set up by the system. Model code of RTU-485 = H’0200.
H’0001	R	Firmware version	The current firmware version is displayed in hex,

e.g. V0.1 is indicated as H’0010.

H’0002

|

R

|

Issue date

| The issue data of the firmware is displayed in hex, e.g. H’1FD0 = K8150 indicates that the firmware is issued on the morning of August 15.
H’0003| R/W| RUN/STOP RTU-485| H’0003 = K1, RTU-485 RUN; H’0003 = K0, RTU-485 STOP.
H’0004| R| Communication format| Displaying the communication format of RTU-485.
H’0005| R| Baud rate| Displaying the baud rate of RTU-485.
H’0006| R| Communication address| Displaying the communication address of RTU-485.
H’0007| R| Number of DI/DO points| High byte stores the number of input points. Low byte stores the number of output points.
H’0008| R| Error code| Recording the current error. See 17.4.4 for the meaing of error codes.
H’0009| R| Historical error code| The number of errors occurring. Range: 0 ~ 32
H’0017| R| Number of special I/O modules| The number of special I/O modules RTU-485 detects.
H’0018| R| Model code of the 1st special I/O module| The model code of the 1st special I/O module connected to RTU-485.
H’0019| R| Model code of the 2nd special I/O module| The model code of the 2nd special I/O module connected to RTU-485.
H’001A| R| Model code of the 3rd special I/O module| The model code of the 3rd special I/O module connected to RTU-485.
H’001B| R| Model code of the 4th special I/O module| The model code of the 4th special I/O module connected to RTU-485.
Communication address| Attribute| Content| Explanation
---|---|---|---
H’001C| R| Model code of the 5th special I/O module| The model code of the 5th special I/O module connected to RTU-485.
H’001D| R| Model code of the 6th special I/O module| The model code of the 6th special I/O module connected to RTU-485.
H’001E| R| Model code of the 7th special I/O module| The model code of the 7th special I/O module connected to RTU-485.
H’001F| R| Model code of the 8th special I/O module| The model code of the 8th special I/O module connected to RTU-485.

Error Codes

Code	Indication	Explanation
0001	Incorrect function code	RTU-485 does not support this function code.
0002	Incorrect operand address	The address of a certain device is not within

Function Codes RTU-485 Supports

RTU-485 complies with the standard Modbus protocol, supporting 7 function codes, which are H’01, H’02, H’03, H’05, H’06, H’0F and H’10. Please refer to the standard Modbus protocol for the specific data format of each function code.

Code	Function	Data type	Applicable address
H’01	Reading the output status of bit device.	bit	DO area: H’0500 ~ H’057F
H’02	Reading the input status of bit device	bit	DI area: H’0400 ~ H’047F

H’03

|

Reading register

|

word

| Area for special functions: H’0000 ~ H’001F
CR for the 1st special I/O module: H’1600 ~ H’1630
CR for the 2nd special I/O module: H’1640 ~ H’1670
CR for the 3rd special I/O module: H’1680 ~ H’16B0
CR for the 4th special I/O module: H’16C0 ~ H’16F0
CR for the 5th special I/O module: H’1700 ~ H’1730
CR for the 6th special I/O module: H’1740 ~ H’1670
CR for the 7th special I/O module: H’1780 ~ H’16B0
CR for the 8th special I/O module: H’17C0 ~ H’17F0
H’05| Writing single datum into bit device| bit| DO area: H’0500 ~ H’057F

H’06

|

Writing single datum into register

|

word

Application of RTU-485

Connection between RTU-485 and Master Device
As a standard Modbus slave, RTU-485 is compatible with pther programmable logic controllers which also comply with Modbus protocol. The example here takes DVP-SV PLC as the master. The PC downloads the ladder diagram to DVP-SV through RS-232 communication port (COM1). When DVP-SV executes the ladder diagram program, it will send out Modbus command through RS-485 communication port (COM2) and conduct remote I/O control on RTU-485. See the figure on the next page for the connection between RTU-485 and the master device:

Application Example

Example 1
- The station No. of RTU-485 is “1”. Write “H’0001” into CR#6 of the 1st special I/O module
Explanations

1. You have to set up the communication format at the beginning of the program. The communication format for the master and slave has to be consistent, e.g. you can see the format is 9600, 7, E, 1, ASCII from this example.
2. After setting up the communication format, you have to set up the communication retention device M1120 of COM2.
3. After M0 is On, set up the sending request flag, and the master device will send out a request message to RTU-485 and write H’0001 into CR#6 of the 1st special module on the right hand side of RTU-485.

Example 2
- The station No. of RTU-485 is “1”. Set up Y0 of the Slim DI/DO on the right hand side of RTU-485.

LED Indicator & Trouble-shooting

There are four LED indicators on RTU-485, which are POWER, RUN, ALARM and RS-485, for displaying the working status and communication connection status of RTU-485.

POWER LED

LED status	Indication	How to correct
Off	No power or the power is abnormal.	Check the power of RTU-485 and see if

the connection is normal.
Green light On| The power of RTU-485 is normal.| —

RUN LED

LED status	Indication	How to correct
Off	RTU-485 is in STOP status.	—
Green light On	RTU-485 is in RUN status.	—

ALARM LED

LED status	Indication	How to correct
Off	The power is in low voltage.	Check if the power of RTU-485 is normal.

Red light On

| Incorrect communication format for RTU-485| Check if the communication format for RTU-485 is correct.
Incorrect communication address for RTU-485| Check if the communication address of RTU-485 is valid.
RTU-485 is not connected to I/O module.| Check if RTU-485 is connected to extension module normally.
More than 8 special I/O modules connected to RTU-485.| Check and make sure that the number of special I/O modules connected to RTU-485 is less than 8.
The number of points on digital I/O module connected to RTU-485 exceeds the range.| Check and make sure the number of input points on digital I/O module connected to RTU-485 is less than 128, and output points also less than 128.

RS-485 LED