Diagnostic hardware for serial datalink

An apparatus for providing fault tolerant serial communications in a network, said network having a plurality of control modules connected one to another, wherein said network is adapted to transmit data messages from one control module to another control module, comprising:

• a first differential receiver having positive and negative input terminals and an output terminal, said negative input terminal being connected to a first positive receiving wire, said positive input terminal being connected to a first negative receiving wire and said output terminal being connected to said one control module;
• means for sensing a short circuit condition between said first positive receiving wire and ground and sensing a short circuit condition between said first negative receiving wire and supply voltage, and delivering a first fault signal in response to either of said sensed conditions;
• a first transmitter having a first positive line driver connected between said one control module and a first positive transmitting wire and a first negative line driver connected between said one control module and a first negative transmitting wire;
• means for sensing the magnitude of current flowing through said first positive transmitting wire, comparing said first positive transmitting wire current magnitude to a first reference current value, and delivering a second fault signal in response to said first positive transmitting wire current magnitude being greater than said first reference current value, and for sensing the magnitude of current flowing through said first negative transmitting wire, comparing said first negative transmitting wire current magnitude to a second reference current value, and delivering a third fault signal in response to said first negative transmitting wire current magnitude being greater than said second reference current, and;
• means for receiving said first fault signal and disabling said first differential receiver in response thereto, receiving said second fault signal and disabling said first positive line driver in response thereto, and receiving said third fault signal and disabling said first negative line driver in response thereto.