Method for transmitting data packets on a data transmission path between two communication subscribers, automation system and computer program

An automation system comprising:

• a first communication subscriber and a second communication subscriber which are connected via a data transmission path and each have a connection unit for transmitting data packets on the data transmission path between the two communication subscribers,
• the connection unit of the first communication subscriber being configured to transmit a first data packet to the second communication subscriber, the first data packet comprising at least data and an identification character,
• the connection unit of the first communication subscriber being configured to determine at least one first acknowledgement character on the basis of the identification character,
• the connection unit of the second communication subscriber being configured to receive the first data packet and, if the first data packet is received, to determine at least one second acknowledgement character on the basis of the first acknowledgement character, and
• to transmit a second data packet comprising the second acknowledgement character to the first communication subscriber,
• the connection unit of the first communication subscriber being configured to receive a second data packet transmitted by the second communication subscriber and
• to check whether the received second acknowledgement character is correlated with the determined at least one first acknowledgement character in such a manner that it confirms the reception of the first data packet, and
• the connection unit of the first communication subscriber being configured to retransmit the first data packet with the identical identifier to the second communication subscriber if the received second acknowledgement character is not correlated with the determined at least one first acknowledgement character or the second acknowledgement character was not received by the first communication subscriber.