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VRD-485 RFID READER WITH RS-485 INTERFACE 

Revision number: 1.01  

Review date: 1 December, 2021

 

www.technotrade.ua

 

 

page 10 from 13 

 

Command 03 

‘Read Holding Registers’

 

 
This command is used for reading registers in range 0x0000 

 0x000B. 

 
Request: 

Request code 

1 byte 

0x03 

Start register 

2 bytes 

0x0000 

… 0x000B

 

Registers quantity 

2 bytes 

0x0001 

… 0x000B

 

 
Response: 

Response code 

1 byte 

0x03 

Quantity of following data bytes 

1 byte 

N x 2 

Data (registers values) 

N x 2 bytes 

 

 quantity of registers 

 
Example: 

REQUEST 

RESPONSE 

Request code 

0x03 

Response code 

0x03 

Start register High number  

0x00 

Quantity of data bytes 

0x04 

Start register Low number 

0x02 

Most significant byte of RFID identifier 
value 

0xA4 

Quantity of High registers 

0x00 

Next byte of RFID identifier value 

0x1E 

Quantity of Low registers 

0x02 

Next byte of RFID identifier value 

0x45 

 

 

Least significant byte of RFID identifier 
value 

0xC6 

 
In this example  there  is a request for identifier code, which is stored in 2  registers  (total size  4  bytes)  at 
address 0x0002. If there is no RFID identifier within the area of the reader action 

 then the returned values 

will contain zeroes. 
 
Response in case of the request error: 

Response code 

1 byte 

0x83 

Error code 

1 byte 

0x02 

 start register number is more than 0x000B 

0x03 

 quantity of requested registers is bigger than memory bounds 0x000B 

 
 
 

Summary of Contents for VRD-485

Page 1: ...VRD 485 RFID reader with RS 485 interface TECHNICAL GUIDE Review date 1 December 2021 ...

Page 2: ...er 1 01 Review date 1 December 2021 www technotrade ua page 2 from 13 CONTENT REVISION HISTORY 3 PURPOSE OF THE DOCUMENT 4 APPOINTMENT 5 TECHNICAL SPECIFICATIONS 5 CONNECTION 6 OPERATION 7 COMMUNICATION PROTOCOL 8 VARIANTS OF SUPPLY AND ORDER INFORMATION 13 ...

Page 3: ...D READER WITH RS 485 INTERFACE Revision number 1 01 Review date 1 December 2021 www technotrade ua page 3 from 13 REVISION HISTORY REV DATE BY SECTION DESCRIPTION 1 01 2013 01 11 Evgeniy Vasyliev All First release ...

Page 4: ...Guide can be downloaded from the VRD 485 RFID web page https www technotrade ua vrd 485 reader html Technotrade LLC hereby permits reproduction of this document as may be required by any of the customers or OEMs wishing to use it This document has been carefully prepared and is believed to be accurate However Technotrade LLC its employees and its agents do not assume responsibility for its use eit...

Page 5: ...al surface and close to sources of electromagnetic interferences TECHNICAL SPECIFICATIONS PARAMETER VALUE Type of contactless identifiers read EM Marine optionally Mifare EM Marine Power supply voltage 8 14 V DC Average consumed current 40 mA Peak consumed current 80 mA Communication interface RS 485 Communication protocol Modbus Maximal possible length of communication cable 1200 m Dimensions 95 ...

Page 6: ... readers on distance not closer of 30 cm to each other 2 Perform marking of holes for mounting of the reader and laying of cables 3 Lay the cable fix it and perform required connections 4 Check correctness of mounting and fix the reader in selected place using screws 5 After complete check of reader operation install decorative caps in holes of screws Note Avoid mounting of the reader directly on ...

Page 7: ...ation to default values In order to perform reset of the reader s configuration set default configuration to the reader it is necessary to make the following 1 Power off the reader 2 Take away the reader s casing and get to its electrical board 3 On electrical board of the reader find 2 contact pads shown on the image below you need to short connect them with each other using tweezers or some othe...

Page 8: ...te the reader in a simplified mode in which it transmits the code of the read RFID identifier without following the Modbus protocol immediately upon reading the card This is done to simplify the work of programmers when a complex solution to a simple problem is not required The reader uses Holding Registers to store the basic settings the code of the identifier which is in the field of action and ...

Page 9: ...0 0x0003 High 0x00 Low 0x00 0x0004 High 0x00 0x00 0xFF Red LED Initial state 1 ON 0 OFF Low 0x00 Duration of state x 10 ms 0x0005 High 0x00 Last state 1 ON 0 OFF Low 0x00 Duration of state x 10 ms 0x0006 High 0x00 Number of cycles for value change Low 0x00 0x00 0xFF Green LED Initial state 1 ON 0 OFF 0x0007 High 0x00 Duration of state x 10 ms Low 0x00 Last state 1 ON 0 OFF 0x0008 High 0x00 Duratio...

Page 10: ...h number 0x00 Quantity of data bytes 0x04 Start register Low number 0x02 Most significant byte of RFID identifier value 0xA4 Quantity of High registers 0x00 Next byte of RFID identifier value 0x1E Quantity of Low registers 0x02 Next byte of RFID identifier value 0x45 Least significant byte of RFID identifier value 0xC6 In this example there is a request for identifier code which is stored in 2 reg...

Page 11: ...0x000B Value for example address High and baud rate Low 2 bytes 0xXXXX Example REQUEST RESPONSE Request code 0x06 Response code 0x06 Register High number 0x00 Register High number 0x00 Register Low number 0x00 Register Low number 0x00 Reader address 27 0x1B Reader address 27 0x1B Baud rate 9600 0x02 Baud rate 9600 0x02 In this example address of the reader is set to 27 and its baud rate is set to ...

Page 12: ...yte 0x10 Register start number 2 bytes 0x0000 0x000B Quantity of registers 2 bytes 0x0001 0x000B Quantity of data bytes 1 byte 0x0002 0x0016 Values 16 bytes Response Response code 1 byte 0x10 Register start number 2 bytes 0x0000 0x000B Quantity of registers 2 bytes 0x0001 0x000B Response in case of the request error Response code 1 byte 0x90 Error code 1 byte 0x02 start register number is more tha...

Page 13: ... internal usage o EXT in case if VRD reader is supplied for external usage and electrical board covered with weatherproof paint z variant of variant of RFID readers o 001 reader equipped with EM Marine RFID reader o 002 reader equipped with EM Marine Mifare RFID readers Examples of order order of VRD RFID reader for internal installation and equipped with EM Marine reader VRD485 INT 001 order of V...

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