System for treating flat pieces , in particular plastic cards , comprising a first module with a first treatment device ; a second module with a second treatment device ; an intermediate device for transferring a flat piece from the first module to the second module ; and a control unit which is coupled to the first module , the second module and the intermediate device , characterised in that the intermediate device comprises: a receiving position and an output position ; a buffering unit with at least a first and a second buffering position ; a first gate element , which is configured to hold the flat piece at the first buffering position , and a second gate element , which is configured to hold the flat piece at the second buffering position ; and a control interface for receiving a control signal; wherein the device is configured such that, depending on the received control signal, the flat piece is received at the receiving position , held at the first buffering position , passed on to the second buffering position and held at the second buffering position , and output at the output position ; wherein the control unit is configured to, if an interruption state of the second module is detected, generate a first control signal such that the flat piece is held at a buffering position of the intermediate device until a second control signal is received and the flat piece is output to the second module . a first module with a first treatment device ; a second module with a second treatment device ; an intermediate device for transferring a flat piece from the first module to the second module ; and a control unit which is coupled to the first module , the second module and the intermediate device , characterised in that the intermediate device comprises: a receiving position and an output position ; a buffering unit with at least a first and a second buffering position ; a first gate element , which is configured to hold the flat piece at the first buffering position , and a second gate element , which is configured to hold the flat piece at the second buffering position ; and a control interface for receiving a control signal; wherein the device is configured such that, depending on the received control signal, the flat piece is received at the receiving position , held at the first buffering position , passed on to the second buffering position and held at the second buffering position , and output at the output position ; wherein the control unit is configured to, if an interruption state of the second module is detected, generate a first control signal such that the flat piece is held at a buffering position of the intermediate device until a second control signal is received and the flat piece is output to the second module . a receiving position and an output position ; a buffering unit with at least a first and a second buffering position ; a first gate element , which is configured to hold the flat piece at the first buffering position , and a second gate element , which is configured to hold the flat piece at the second buffering position ; and a control interface for receiving a control signal; wherein the device is configured such that, depending on the received control signal, the flat piece is received at the receiving position , held at the first buffering position , passed on to the second buffering position and held at the second buffering position , and output at the output position ; wherein the control unit is configured to, if an interruption state of the second module is detected, generate a first control signal such that the flat piece is held at a buffering position of the intermediate device until a second control signal is received and the flat piece is output to the second module . <EOS>