Serial communications protocol for safety critical systems
First Claim
1. A method for establishing communications between at least two independent software modules in a safety critical system, comprising:
- providing a media connection between software modules, wherein the software modules employ a communications protocol and participate in a bi-directional master-slave relationship between a master module and a slave module;
sending messages from said master module to said slave module and from said slave module to said master module, each message comprising an arbitrary length of data comprising optional data, enabling the master module and slave module to detect errors in each message and the master module to control and obtain status from the slave module, and the message further enables the slave module to return data and status information to the master module; and
employing a safety critical communications watchdog function between the master and slave modules, monitoring communications quality between the master and slave modules bi-directionally, wherein the safety critical communications watchdog function comprises the master module and the slave module simultaneously counting time between receiving data packets from the other module and generating a fail condition when a data packet has not been received in a predetermined amount of time,wherein communications protocol comprises transmitting bytes in a packet consisting of;
a start indication;
a message identifier;
an optional service identifier;
a class identifier;
an arbitrary length of optional data;
a checksum; and
a checksum complement.
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Accused Products
Abstract
A method and system of establishing communications between at least two independent software modules in a safety critical system, such as a medical system, is provided. The design comprises providing a media connection between software modules, wherein the software modules employ a communications protocol and participate in a bi-directional master-slave relationship between a master module and a slave module. The design further comprises sending an arbitrary length of data between the master and slave modules, wherein the arbitrary length of data is used by the master module to control and obtain status from the slave module, and sending arbitrary data further enables the slave module to return data and status information to the master module. The design also employs a safety critical communications watchdog between the master and slave modules, wherein the safety critical communications watchdog monitors communications quality between the master and slave modules. The protocol comprises bytes transmitted using a packet consisting of a start indication, a message identifier, an optional service identifier, a class identifier, an arbitrary length of data pertinent to the medical device comprising optional data, a checksum, and a checksum complement.
29 Citations
18 Claims
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1. A method for establishing communications between at least two independent software modules in a safety critical system, comprising:
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providing a media connection between software modules, wherein the software modules employ a communications protocol and participate in a bi-directional master-slave relationship between a master module and a slave module; sending messages from said master module to said slave module and from said slave module to said master module, each message comprising an arbitrary length of data comprising optional data, enabling the master module and slave module to detect errors in each message and the master module to control and obtain status from the slave module, and the message further enables the slave module to return data and status information to the master module; and employing a safety critical communications watchdog function between the master and slave modules, monitoring communications quality between the master and slave modules bi-directionally, wherein the safety critical communications watchdog function comprises the master module and the slave module simultaneously counting time between receiving data packets from the other module and generating a fail condition when a data packet has not been received in a predetermined amount of time, wherein communications protocol comprises transmitting bytes in a packet consisting of; a start indication; a message identifier; an optional service identifier; a class identifier; an arbitrary length of optional data; a checksum; and a checksum complement. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A medical device system configured to manage communications therein, the system comprising:
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a master device and a slave device; wherein the master device and the slave device each comprise a plurality of software modules comprising at least two software modules; and a media connection between the master device and the slave device; wherein the master device and the slave device are capable of communicating via the plurality of software modules using implicit messaging, the implicit messaging comprising transmitting an implicit message containing no data object description and comprising an arbitrary length of data comprising optional data from said master device to said slave device and from said slave device to said master device to detect errors in and verify integrity of the implicit message; wherein the plurality of software modules provide a medical event safety critical communications watchdog function to verify communications integrity over the media connection, wherein the safety critical communications watchdog function comprises the master device and the slave device simultaneously counting time between receiving data packets from the other device and generating a fail condition when a data packet has not been received in a predetermined amount of time, wherein the bandwidth efficient communications protocol comprises bytes transmitted using a packet consisting of; a start indication; a message identifier; an optional service identifier; a class identifier; an arbitrary length of optional data; a checksum; and a checksum complement. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A safety critical system comprising:
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a master medical device; and a slave medical device, wherein the devices comprise a plurality of software modules capable of communicating via a bandwidth efficient communications protocol, and wherein the communications protocol comprises bytes transmitted using a packet consisting of; a start indication; a message identifier; an optional service identifier; a class identifier; an arbitrary length of data pertinent to the medical device comprising optional data, wherein length of the arbitrary length of data depends upon at least one of the class identifier, message identifier, and optional service identifier; a checksum; and a checksum complement; and wherein the master medical device and the slave medical device each provide a medical event safety critical communications watchdog function to verify communications integrity over the media connection, wherein the safety critical communications watchdog function comprises the master medical device and the slave medical device simultaneously counting time between receiving data packets from the other medical device and generating a fail condition when a data packet has not been received in a predetermined amount of time. - View Dependent Claims (17, 18)
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Specification