ADI-524

The ADI-524 is 4 channel 4-20mA analog to RS485 converter using standard Modbus-RTU protocol. It has dedicated RS485 port for output which need power supply to lit up device or It can work over single USB port having power supply and RS485 output in it.

Please read carefully before starting. Also read the product safety information.

General information

Download technical specification Technical Specification

ADI-524 has 4 opto-isolated analog inputs and RS485/USB output. It is also featured with isolated 24V power output to feed 4-20mA sensors/devices. For baud rate and Modbus address configuration to be done using DIP switch.

Additional USB port make this device perfect to use with industrial computers and gateways having dedicated USB port, as this product is designed according to industry-standards.

It can be mounted on standard DIN rail by using clamps.

Hardware informations

This interface converted is made of single PCB, which is fitted in aluminum housing. The housing is made of a thick, strong aluminum profile with two end plates also made from aluminum. The surface of the housing is finished by anodizing. 

At the bottom of the housing there are slots through which DIN rail clamp or any other clamp can be mounted by t-nuts.

Front view dimensions

ADI-524-dimensions-top.png

Side view dimensions

ADI-524-AG-dimensions-B.png

Interfaces

Top view connector and indicators

ADI-524-connectors-A.png

Bottom view connector

ADI-524-connectors-B.png

Configuration Manual

Please read carefully before starting. Also read the product safety information.

Wiring and connection

The ADI-524 can be powered from a DC power supply in the range of 8-36V. Also, it can be powered from the USB port of a computer or IoT gateway. Both power sources can be connected simultaneously without fear of damage.

ADI-524-sonnecting-via-usb.png

In order to connect sensors with a 4-20mA output, it is necessary to provide them power in the loop. Here are some possible connection methods. Either the built-in isolated 24V power supply can be used or an external current loop power supply can be used.
All current inputs marked as - on the housing are connected together. The isolated 24V, on the other hand, has no galvanic connection to any of the inputs.


Connection Diagrams

Built-in 24V

Connection of four RTD converters using the built-in 24V power supply.

ADI-524-conncetion-1.png

External 24 V

Connection of four RTD converters using the external 24V power supply.

ADI-524-conncetion-2.png


Modbus configuration

It is necessary to set the serial port parameters and the Modbus address using the DIP switch before powering on the device. (reference table for both are given below)

Make sure to reboot/restart device irrespective of any change in DIP switch to be reflected in hardware

MODBUS Serial Port Parameter
Parameter Option/range
Baudrate 9600 – 115200 configurable
ata bit 8
Parity None
Stop bit 1

MODBUS Baudrate Configuration

User can set the baud rate using 2 Bit DIP switch. This allows to set baud rate between 9600bps to 115200bps as shown below table.

Baudrate
SW1
SW2
9600 OFF
OFF
19200 ON
OFF
38400 OFF ON
115200 ON ON

After setting up the switch, it is necessary to restart the ADI by disconnecting the power supply and, if using USB power, to disconnect it.


MODBUS Address configuration

User can set the slave ID address using 4 Bit DIP switch. This allow 0 to 15 different IDs to be set. The number below the switches are added together and the result will be identifier of the device slave ID.

Slave ID SW3 SW4 SW5 SW6
1
OFF
OFF OFF OFF
1
ON
OFF OFF OFF
2
OFF ON OFF
OFF
3
ON
ON
OFF OFF
4
OFF
OFF ON
OFF
5
ON
OFF ON
OFF
6
OFF ON
ON
OFF
7
ON
ON
ON
OFF
8
OFF OFF OFF ON
9
ON
OFF OFF ON
10
OFF ON
OFF ON
11
ON
ON
OFF ON
12
OFF OFF ON
ON
13
ON
OFF ON
ON
14
OFF ON
ON
ON
15
ON
ON
ON
ON

Protocol Description

Overview

The MODBUS protocol is a widely used communication standard in industrial automation, facilitating master-slave data exchange. It is known for its simplicity and flexibility, making it suitable for a range of applications in connecting intelligent devices.

In MODBUS communication, messages sent from the master to a slave device contain key components: the slave's address, a command (such as "read register" or "write register"), the associated data, and an error-checking field (using LRC or CRC for checksum). As a messaging protocol, MODBUS is independent of the underlying physical layer, meaning it can be implemented over various mediums like RS485 or USB-to-serial interfaces.


USB interface

ADI-524 has a built-in USB to serial converter, you can plug USB cable and start device configuration as there is no need to install any additional drivers on most operating systems. However, if you find that you need to install drivers, you can download driver - .V1.00 driver.zip

The ADI-524 allows operation via only one interface at a time. Either RS485 or USB. DIP switch settings are necessary when using both interfaces


MODBUS RTU Framing

The ADI-524 module supports standard RTU Modbus protocol for getting the input status and setting/getting the relays status. RTU Modbus Protocol frame is illustrated below:

Start Address Function Data
RC Check End
≥ 3.5 Char 4 Bits

8 Bits

N*8 Bits 16 Bits ≥ 3.5 Char
  1. Start Address: This identifies the specific device or slave on the network. Each device has a unique address to differentiate it from others.
  2. Function Code: Specifies the type of operation being requested. Common function codes include:
          - 0x03: Read Holding Registers
          - 0x06: Write Single Register
          - 0x10: Write Multiple Registers
  3. Starting Address: The address of the first register from which data will be read or to which data will be written
  4. Number of Registers: Indicates how many registers should be read or written, starting from the specified address.
  5. CRC (Cyclic Redundancy Check): This is a checksum used to verify the integrity of the data. It is calculated based on the previous fields and helps detect errors in the transmitted data.

Each part of the request plays an important role in ensuring the correctness of Modbus communication. The start address and function code define the operation, and the CRC checksum protects the accuracy of the message.


MODBUS Command examples

04 function code for reading value from input.
Modbus dear query message

Command: read analog input 1
Byte
Byte description Example (HEX)
0
Slave ID 01
1
Function code 04
2
Starting address High 00
3
Starting address Low 00
4
Number of Registers High 00
5
Number of Registers Low 02
6
CRC AB 71
7
CRC CD CB
Start

Slave address
XX

Function code
04
Starting Number

CRC ABCD

71 CB

End
High Low High Low
00
00
00
02

Modbus response

Response: Analog Input - 13.40mA
Byte
Byte description Example (HEX)
0
Slave ID 01
1
Function code 04
2
Byte Count 04
3
Data 1 41
4
Data 2
6C
5
Data 3
CC
6
Data 4
CD
7
CRC AB BB
8
CRC CD 30

The number in 32-bit floating point HEX format 0x416CCCCD in decimal is: 13.40

Start

Slave address
XX

Function code
04
Number of bytes Data Error check

 

End
First register
Second register
Data 1
Data 2
Data 3
Data 4

Safety information

Operating environment

Use in inappropriate conditions may damage the device or shorten its life.


Electrical and power supply safety

Only a person with qualification and appropriate knowledge should install the device.


Malfunctioning and damaged device

What to do and what not to do