CANopen in a heart-lung machine
Source: CAN Newsletter September 2009
Heart surgeries for conditions such as valvular heart disease require that the heart is temporarily stopped and blood supply to the heart is cut off. When this happens, cardio-pulmonary functions (the oxygenation and circulation of the blood) temporarily cease. The heart-lung machine is a medical device, which takes over cardio-pulmonary functions while the heart is stopped. Senko Medical Instrument Manufacturing developed Japan’s first heart-lung machine, and is a Japanese industry leader in this field.
Safety is the first priority for a heart-lung machine. In this context, "safety" means that the system will continue to provide extracorporeal circulation of the blood, and not stop under any circumstances.
Until recently, the company used such communication protocols as RS‑232 or HDLC (high-level data link control) for heart-lung machine control systems, utilizing a protocol analyzer or oscilloscope to verify communications. However, the creation and validation of original protocols required an enormous amount of time. The difficulty of achieving superior reliability while avoiding lengthy development periods hindered the development of advanced functions for heart-lung machines.
Selecting CANopen
Company’s solution was to introduce the use of standard communication protocols. The first candidate was CAN, a communication protocol, which has achieved a track record in the automobile industry, but information on CAN is not readily available. Therefore, a standardized application-layer protocol CANopen was chosen. This allowed Senko’s medical devices to use the CANopen tools from Vector - a company offering development tools, embedded source code expertise and technical support. However, there are still some concerns about developing firmware that would meet complex specifications, since CANopen is an open and expandable protocol.
