FORM2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
PROVISIONAL SPECIFICATION
(See section 10; rule 13)

1. Title of the invention.

CAN BUS BASED INTELLIGENT ELECTROMECHANICAL TOTALISER (EMT)

2. Applicant(s)
(a) NAME :
(b) NATIONALITY :
(c) ADDRESS :

LARSEN & TOUBRO LIMITED
An Indian company
L & T House, Ballard Estate, Mumbai 400 001, State of Maharashtra, India

3. PREAMBLE TO THE DESCRIPTION
The following specification describes the invention

TITLE OF INVENTION
CAN BUS BASED INTELLIGENT ELECTRO-MECHANICAL TOTALISER (EMT).
FIELD OF INVENTION
The present invention relates to an encapsulated Electro-Mechanical Totaliser (EMT). More particularly, the invention relates to an intelligent EMT and a microcontroller board sealed mechanically thereby providing handshaking betweent the microcontroller and the totalizer unit thus preventing tampering of the EMT.
BACKGROUND AND THE PRIOR ART:
The Electro-Mechanical Totaliser (EMT) (Fig.l) is a mechanical counter driven by electric pulse of 5 Volt. EMT is used to count (totalize) fuel dispensed by the corresponding nozzle with resolution of either 100ml or lLt.
Earlier an EMT was connected to the main board (where dispenser logic resides) via 6 pin connector (Fig. 2). The pin description is as below:
Pin No. Description
1, 2 Supply (24V)
3, 4 EMT Drive pulse output
5 EMT detect
6 Ground
EMT being a slave device was driven by the main board with raw pulses given on pin no. 3 or 4 . A simple EMT detection logic was built using pin no. 5 and 6, where at pin no. 5 pull up to VCC (5 Volt) is connected. Whenever EMT was plugged in, both


the pins were shorted and potential at pin no. 5 goes to zero which was sensed by the main board controller as EMT presence.
In previous dispenser electronics EMT is connected directly on the port pins of main controller board. The EMT detection logic was built using two pins; one pin was pulled up to VCC (5V) and other was ground. Whenever EMT is plugged in pins got short and this was sensed by the main controller as an EMT presence. As there is no handshaking between main board and EMT, dispenser could be tampered with by removing the EMT and shorting those two pins.
The present inventors have now found that control area network (CAN) bus when integrated with the EMT and the main board of the micro-controller provides a secured communication between micro controller unit and the EMT whereby communication take place in an encrypted form not allowing tampering of a communicated message during its transition.
Also each Intelligent EMT is mapped to the corresponding nozzle by the configuration message from the main board. At every dispense there is EMT presence check along with the following error condition checks:
. No EMTCoil voltage.
• EMT coil short.
. EMT not configured.
• EMT wrong configuration.
. EMT not present.
24V absence
OBJECTS OF THE INVENTION:


Accordingly, one aspect of the present invention is to encapsulate the EMT and a microcontroller board and sealing it mechanically so as to avoid the simulation of the EMT presence to the system.
Yet another object is the communication between Intelligent EMT and main board over CAN bus using a propriety protocol.
Another aspect is to encrypt the communication.
DETAILED DESCRIPTION OF THE INVENTION:
Accordingly, the present invention relates to an intelligent mapping of EMT.
Each Intelligent EMT is mapped to the corresponding nozzle, which is configured by the configuration message sent by the main board during power on condition on pressing a particular key sequence on the main board. Nozzle ID from the configuration message is stored in the controller flash along with the signature.
The device ID of the Intelligent EMT is decided by the DIP switch on the EMT board.
On the nozzle up (dispense start) the main board queries for the EMT presence. Intelligent EMT board replies to the query according to the following scenario:
o Intelligent EMT is not configured: - Intelligent EMT will reply with message "NO CONFIGURATION".


o Intelligent EMT is configured with wrong nozzle ID: - Intelligent EMT will reply with message "WRONG CONFIGURATION".
o Intelligent EMT is configured with correct nozzle ID: - Intelligent EMT will reply with message "EMT PRESENT".
During dispense main board sends the EMT update query along with the count and nozzle no, count is stored inside the ram of Intelligent EMT board and electro-mechanical totaliser is updated by the same. Intelligent EMT board replies to the query according to the following scenario:
o 24 V (required for EMT coil) is not present: Intelligent EMT will reply with message "NO COIL VOLTAGE".
o EMT coil is open or EMT is removed from the board: - Intelligent EMT will reply with message "EMT REMOVED".
o EMT coil is short: - Intelligent EMT will reply with message "EMT COIL SHORT".
o Nozzle No. mismatch: - Intelligent EMT will reply with message "WRONG CONFIGURATION".
o No error condition: - Intelligent EMT will reply with message "SUCCESS".
At power fail NMI (power fail interrupt) is generated, in the interrupt routine the EMT update count is stored in the non-


volatile memory. And at immediate next power on EMT will be updated with the count stored in the memory.
In the prior art, since there was no handshaking between EMT and main board, the EMT could be tampered with by removing the EMT from the main board and shorting the pin no. 5 and 6 on the connector of main board (Refer Fig. 3) . This caused the simulation of EMT presence to the system.
To avoid the above mentioned problem, the present inventors have encapsulated the EMT and a microcontroller board and sealed it mechanically (Intelligent EMT: Fig.4). The communication between Intelligent EMT and main board is over CAN bus using a propriety protocol. Also the communication is encrypted.