Ahead of Lok Sabha Polls, EC Answers Longstanding Query on How EVMs Get Signals 

In 2021 former IAS officer Kannan Gopinathan raised serious questions over the ECI’s claim that EVMs are stand-alone machines which are neither accessible remotely from any network nor can be connected to any external devices

New Delhi: The Election Commission of India has updated on January 30, the list of frequently asked questions (FAQ) on its website, in which it has addressed how signals are received and sent between the EVM (electronic voting machines) and VVPAT (voter verified paper audit trails).

The FAQs come as opposition parties have raised questions about the role of EVMs in the run up to the Lok Sabha elections.

Question 86 of the FAQs answers how signal or command flow between various units of EVM i.e. between ballot unit (BU), control unit (CU) and VVVPAT. It also answers if the VVPAT which is kept along with BU inside the voting compartment of the voter receives any signal or command from BU and vice-versa.

The ECI has stated in its answer that in M3 EVMs (the current model that is being used), the CU acts as the Master “irrespective of the position in which it is placed or connected.”

“BU and VVPAT act as Slave units in the connected network, which receive commands from CU to act as per the application programme. BU and VVPAT do not communicate with each other. It is the CU that communicates with both the BU and VVPAT. When a voter presses a candidate button on BU, the BU sends the button number to CU and in turn, the CU communicates to VVPAT to print the slip of the corresponding button number. Only after printing and cutting of the printed VVPAT slip, the CU registers the vote,” it says.

The website shows a diagram to explain the signal flow details in the M3 model EV-VVPAT.

It states that in the M3 model,”Master-Slave bus architecture is used.”

Under this model the VVPAT can be connected anywhere in the EVM M3 bus. The Control Unit (CU) implements communication, command processing, handling of key operations and handling of all the commands/responses to/from BU and VVPAT. 

“Communication on the bus is initiated by the “Master” (CU) with a “Command” to a “Slave” (BU & VVPAT). The ‘Slave’ which is constantly monitoring the bus for “Commands” will recognise only the ‘Commands’ addressed to it and will respond by performing an action and by returning a ‘Response’. Only the Master can initiate a command. CU is always the Master in the ECI M3 EVM system setup,” it states.

In a series of tweets in 2021, former IAS officer Kannan Gopinathan raised serious questions over the ECI’s claim that EVMs are stand-alone machines which are neither accessible remotely from any network nor can be connected to any external devices. With the introduction of VVPAT, these claims do not hold as these machines are apparently connected to laptops or symbol loading units (SLUs).


VVPATs were inducted into the electoral process in 2013 to provide an additional layer of scrutiny against possible EVM manipulation. They allow physical tallying of votes. 

Gopinathan said that with the addition of the VVPAT mechanism, the voting process became “vulnerable and suspicious” instead of being strengthened.

He said that EVMs are not stand-alone machines as they are connected to laptops of SLUs and it is not single programmable as they are showing names and symbols of candidates. “How do you store it? You need a programmable memory. It is not a stand alone machine and it has a programmable memory,” he said.

“It has every aspect of a full fledged computer apart from a screen,” he said in an interview to The Logical Indian.

Gopinathan, who was the returning officer for Dadra and Nagar Haveli in the 2019 Lok Sabha elections subsequently stepped down as an IAS officer over the reading down of Article 370 in Jammu and Kashmir the following year.

Speaking to The Telegraph, Gopinathan said that while he has not examined the poll panel’s FAQ, the current process does not fulfil the demands of a fair election.

“A fair election is one where the voter has agency to verify the vote, and the candidate can verify counting. The current process fulfills neither. Verification would mean the ability to accept or reject what is registered on the VVPAT slip that one sees,” he said to the outlet.

“The Conduct of Election Rules say that in case of a mismatch between the CU and VVPAT vote tallies (five are tallied in every Assembly segment), the latter is to be counted for that machine. Thus, the EC itself considers the VVPAT more reliable than the CU. Then why does it rely on the CU count for the overall result?”