Abstract: A method for securely transmitting data messages in an HVDCT system. Each transmitting unit is connected to each receiving unit via at least two connection channels. Each data message includes a message counter that uniquely characterizes the data message, and each transmitting unit transmits the data message to each receiving unit via all of the connection channels. Each receiving unit calculates a comparison counter and compares it with the message counter in the received data message. If the message counter and the comparison counter do not match, a repetition request is transmitted to the transmitting unit for the purpose of transmitting a message counter that corresponds to the comparison counter. After the repetition request has been received, the transmitting unit accesses a transmission buffer, and the data message whose message counter corresponds to the comparison counter of the repetition request is transmitted via all of the connection channels.

Abstract: A method for securely transmitting data messages between at least one transmitting unit and at least one receiving unit of an HVDCT system. Each transmitting unit is connected to each receiving unit via at least two connection channels. Each data message is provided with a message counter that uniquely characterizes the data message, and each transmitting unit transmits the data message to each receiving unit via all of the connection channels. The message counter is calculated using an incrementing rule that is clocked by the transmission of the data messages. Each receiving unit uses the same incrementing rule, which is clocked by the reception of data messages, to calculate a comparison counter. Each transmitting unit stores data messages which have already been transmitted in a transmission buffer, and the receiving unit compares the message counter of each received data message with the comparison counter.