RFID

Application

Used for monitoring objects with restricted access. Enables alerting and identification of individuals accessing the object using proximity cards. The access authorization module is part of the remote monitoring kit for the heat distribution node. It cooperates with the dedicated object controller Smart GPRS 300 type (it is also possible to connect to the GPRS Controller using an additional adapter). Popular RFID transponders in any form (card, keychain) are used for authorization.

Operating principle

The module is used to identify individuals entering the heat distribution node room. It is installed inside the room (which allowed for the use of an economical, non-“vandal-proof” casing). In stand-by mode, the module waits for the door to open, the transponder reading circuit is disabled, and the only activity are periodic (every few minutes) responses to reading the MODBUS control register (this is to detect any potential module failures early). When the door is open (NC contact open), the transponder reader and optical-acoustic reminder signaling the need for authorization are activated. Once the code has been correctly read or the waiting time has elapsed, the reader circuit and signaling are turned off, and the module sets the low state on the request line. This allows the Smart GPRS 300 firmware to detect the entry event and read the 5-byte transponder identifier (all zeros if none is available) using the MODBUS RTU protocol. The use of this data depends on how the master monitoring system is organized. Until the door is closed, the module keeps the request line low, and the reader remains inactive.

Technical data:

Primary power supply

12 ÷ 24 VDC / power supply current < 50mA

Communication

Communication interface * M-BUS system bus, UART 2400/8/1/EVEN

Supported communication protocol MODBUS RTU with limitation to read RFID Parameters

Supported transponder type UNIQUE (125 kHz, Manchester coding)

RFID identifier format 5 bytes, compliant with TRD 80 Classic

Operating range approx. 6 -10 cm – depending on transponder design

Transponder waiting time 20 s

Sound + LED signal indicating door opening

volume approx. 85 dB/10 cm

frequency 3.1 kHz modulated

Binary inputs for door opening sensor

contact type

voltage on open contact 5 V

closed contact current 2 mA

Outputs

one open collector output adapted to connect to DI Smart GPRS 300 input

Connections for power supply and communication

RJ45 connector (network) identical to SMART GPRS 300 module (1:1 connection)

Connection list on RJ45 connector

– 1,2 + 12 ÷ 24V

– 3,4 GND

– 5 not connected

– 6 binary output

– 7 GND MBUS

– 8 + MBUS

Casing ** plastic, IP 54 protection class for wall mounting

Dimensions width: 74 mm, height: 88 mm, depth: 42 mm

* design allows for module construction with a different interface (e.g. RS 485) and other transmission parameters.

** possible to manufacture with better seals in IP 65 version;